Self watering for pots

Contents

All About Self-Watering Planters & Containers

Self-watering containers are a must-have if you’re forgetful, live in a hot or dry climate, or you’re just not home very often. They’re also helpful if your containers are in an area that’s not convenient to a water spigot, such as a balcony, if you’re growing plants that don’t like to dry out, or if the plants don’t like getting their leaves wet.

In the video below, I walk you through:

  • the features of self-watering containers,
  • how they work,
  • different types (including DIY options), and
  • how to plant and grow things in them.

Or just keep reading for all the details, including my top recommendations.

What is a self-watering container or planter?

Contrary to what the name implies, a “self-watering planter” doesn’t actually water itself. But it does provide a consistent source of moisture to the plants growing in it and allows you to water less frequently.

Although designs may differ somewhat across brands and planter styles, the basics are the same. Water is poured directly into a water reservoir and then “wicked” into the planting container above the reservoir.

Parts and Common Features

Not all self-watering planters will have all of the items listed below, but they typically include a:

  • water reservoir
  • planting container
  • wicking mechanism
  • fill tube
  • overflow hole or spout
  • water level indicator
  • drainage hole and plug

The top section of a self-watering planter is usually for your potting mix and plants, while the bottom contains the water reservoir. Reservoirs vary in size, often in proportion to the overall size of the container. In larger containers, it’s not unusual to have a 5-gallon reservoir, while smaller planters may have only a 1-gallon capacity (or even less). Look for a planter with a water reservoir that’s large enough to provide adequate moisture for the volume of potting mix in the container above and that you won’t have to fill every day.

A fill tube or opening of some kind is used to pour water directly into the reservoir. This can vary from a simple tube placed in the corner of the planter to a hole in the planter rim or an opening in the container wall that gives direct access to the reservoir. Some tubes have caps to keep pests and debris out of the reservoir. (I like that option but unless the cap is attached to the container, I always end up losing it!)

Some planters have an indicator that shows how much water is in the reservoir. These are convenient, as you’ll have a better idea of when the reservoir needs to be refilled.

All planters should have an overflow mechanism that allows water to drain out if the reservoir is filled to full. This prevents plants from sitting in water (which would rot them pretty quickly) if you overfill the reservoir by mistake and keeps water at the right level after a heavy rain.

Finally, a drainage hole with a plug allows you to drain the container at the end of the season (don’t leave water in the reservoir during the winter if there’s any chance it could freeze) or bring it indoors.

How do self-watering planters work?

There are two basic ways in which self-watering planters move water from the reservoir into the planting container above, both of which rely on capillary action. If you’ve ever dipped one end of a paper towel in water, you’ll have seen capillary action in action as water slowly creeps across the rest of the paper towel. In self-watering systems, you’ll the following designs:

  1. A “wick” is placed inside the container, with one end in the water reservoir and the other end in the potting mix. This can be a strip of capillary mat, an absorbent tube-shaped plug or a thick string. The wick basically sucks water out of the reservoir and delivers it to the potting mix.
  2. The planting container is designed with a section that sits inside the water reservoir, placing potting mix directly in contact with the water. Water from the wet mix in that section is pulled up into the rest of the planting container through capillary action. This is the most common design.

A third design sometimes sold as being “self-watering” has a perforated separator between the reservoir and planting container (so potting mix is never in direct contact with the water below). It relies on evaporation from the reservoir to moisten soil at the bottom of the planter and, from there, spread it throughout the container. In my experience, this is the least effective of the self-watering container designs.

How are they helpful?

Consistent Moisture and Less Frequent Watering

I like self-watering containers because they provide consistent moisture for your plants without having to constantly water by hand. At our headquarters here in Tucson, my planters that don’t have a self-watering system need to be watered twice a day during the summer to keep them from drying out. On the other hand, my self-watering planters generally go a week between waterings (and the TruDrop planters can go two to three weeks, even in 100F+ temperatures!).

The consistency is especially helpful for plants that don’t react well to inconsistent watering, such as tomatoes; you’ll probably find that you have a better yield if you use self-watering planters for your vegetables. I’ve had fantastic results growing veggies in the Vegepod (a self-watering planter that won our Golden Shovel Award in 2018) and now use it for all my lettuce, beans, squash and tomatoes.

Note: Some plants, such as cactus and succulents, do not grow well in constantly moist conditions. Don’t plant them in a self-watering container.

More Efficient Use of Water

Because water is in an enclosed reservoir, it doesn’t evaporate directly into the air; instead, it goes directly to the plant’s roots. In contrast, when you spray your plants (or even when you use a watering can), a lot of that water goes on the ground or the plant’s leaves, where it evaporates without benefiting the plant.

Prevents Plant Diseases

Some plants, like tomatoes and phlox, are prone to fungal diseases if the leaves get wet. By watering from below, a self-watering container bypasses this issue, resulting in healthier plants.

How to set up a self-watering container

At this point, if you haven’t watched the video (above), this would be a good time to check it out, so that you can see a demonstration of how a self-watering planter works and how to plant it.

But, generally, you’ll want to follow these steps:

  1. Insert the parts into the container (according to instructions for your specific self-watering system).
  2. Add any type of moist potting mix to the planting container. Some companies sell mixes specific for self-watering containers but any high-quality mix will work. The key is to moisten it before placing it in the planting container. If you use dry potting mix, it will not work.
  3. Pack the moistened mix into the depressions at the bottom of the planting container (that’s where the moisture gets wicked up into the soil/roots) OR if your system has a wick, be sure one end (or both ends – read the instructions for your planter) is placed in the water reservoir.
  4. Plant your favorite plants in the container. Don’t compact the potting mix but do firm in the plants so they’re well-supported.
  5. Water from the top to remove air pockets and settle the roots (add additional potting mix if needed). This is typically the only time you’ll water from above; after this, just fill the reservoir directly.
  6. Wait a while for water to percolate down through the potting mix into the reservoir. Then fill the reservoir completely.
  7. Refill the reservoir as necessary when the water level is low. Do NOT let it dry out. If it does, water from above to ensure that all of the potting mix is thoroughly moistened before filling the reservoir again. Dry planting mix will not wick water so even if you fill the reservoir, the plants won’t receive the moisture they need.

At the end of the season …

Remove the potting mix from the planter each year (you can use it again if desired) and clean out the reservoir. Roots tend to grow down into the reservoir and can completely fill it or clog the wicking wells. This is especially true for plants like sweet potato vine; they grow exceptionally well in a self-watering planter but the roots are aggressive in their search for water, sending huge masses of roots into the reservoir and quickly sucking it dry.

In areas with cold winters, drain the planter before storing it for the winter. Any water that freezes inside the reservoir can crack the walls.

Which types of containers are available/recommended?

Self-watering containers vary by brand, style, size, features, appearance and more, just like most planting containers. I’ve used many different types over the years – below are my favorites.

Most Attractive

If you’re looking for something more decorative, the one in the video is by Lechuza, and I highly recommend it. After 7 years, it still looks like new and works flawlessly.

Lechuza Cubico Cottage 30 Self-Watering Garden Planter for Indoor and Outdoor Use, Mocha Wicker Lechuza produces many different styles, although they lean toward a more modern look. $81.25 SEE OUR REVIEW See it on Amazon

Best for Growing Vegetables

For veggies, I go with something more utilitarian, rather than decorative, and large enough to grow a decent crop. My favorites are below (some are also shown in the video).

Vegepod – Raised Garden Bed – Self Watering Container Garden Kit with Protective Cover, Easily… Available in three sizes and comes with a cover and watering tube. Produces the best veggies I have ever grown. Note that the price shown here is for a cover only; the small Vegepod starts at around $169 but is worth every penny! $199.00 SEE OUR REVIEW See it on Amazon Tomato Success Kit Tomatoes need enough soil for their large root systems. I can grow two tomatoes in this system quite nicely. $89.95 SEE OUR REVIEW See it on Amazon

Larger Self-Watering Planters

Self-watering planters come in a wide range of shapes and sizes. Two I particularly like are:

Galvanized Self-Watering Planter Square, Tall Available in a variety of sizes and heights, with and without wheels to move it around. This one has a unique wicking system that works extremely well. $119.00 SEE OUR REVIEW See it on Amazon Terrazza Trough Planter, Loden Also available in a variety of sizes and with add-on parts to extend the length or add a corner. It looks nice and holds up well to sun and heat. $129.00 See it on Amazon

Outstanding Capacity

One self-watering container that’s not shown in the video but is truly outstanding, is the TruDrop planters from Crescent Garden. The large Rim planter can go 3 weeks between refills even in the extreme summer heat.

Crescent Garden Self Watering Rim Planter with TruDrop System, 22″, Midnight If I had to pick just one self-watering container for growing thirsty plants in a hot, dry climate, this would be the one.

Self-Watering Inserts

You can make your own self-watering container if you’re more DIY-inclined; a simple internet search will reveal several different options. But I prefer to do it the easy way – I buy self-watering pot reservoirs from Gardener’s Supply.

Gardener’s Supply Company Self-Watering Pot Reservoir for Planters, Gallon These inserts come in different sizes for different pots, so you can use them in any regular pots you already own. $24.95 See it on Amazon

I’ve reviewed many self-watering containers so if the list above doesn’t meet your needs, check out all the reviews.

See our reviews of self-watering containers >>

And that’s it! Let us know if you try out a self-watering container for the first time, we’d love to hear how it works for you!

Last update on 2020-02-01 / Affiliate links / Images from Amazon Product Advertising API

I like to garden and grow houseplants, but I also like to travel. I finally figured out how to combine my two pleasures successfully—self-watering pots. With self-watering pots and planters I can go away knowing my plants will get the water they need. Believe it or not, I can leave my houseplants for as long as a month! Self-watering containers have other advantages: they take the guesswork out of watering, help prevent root rot, and make it easier for busy people to maintain their gardens. It’s also great if you have plants in places that are hard to reach.

How to Use Self Watering Planters

Self-watering planters have reservoirs that hold water. The amount of water varies with the size and style of the planter. Some have a wicking material that transports the water to the soil, while others rely on capillary mats and/or evaporative action to moisten the soil. A refill tube makes it easy to refill the reservoir with water. Some self-watering planters include a water level indicator or a window in the reservoir to help you judge when you need to add water.

A lightweight, well-drained soil mix works well in self-watering containers. It promotes growth and aeration. While proportions and ingredients vary, a typical mix may contain equal parts perlite and peat. Shellfish compost is another common component of some container mixes. Frequency of watering depends on the size of the reservoir, the size of the container, the type of plants, and environmental conditions such as sun, wind, and rain. For indoor plants, heat and air conditioning affect how quickly the plants use up the water in the reservoir.

Some self-watering containers include staking systems designed for tomatoes and other crops that need support. You can also buy self-watering raised garden containers, which are ideal for people who prefer to garden at waist height. Containers may come with casters for easy moving, fertilizer, and/or mulch.

Interested in making your own self watering pot?

You can buy self-watering planters in all shapes and sizes, from individual pots to hanging baskets to window boxes. You can also buy conversion kits and transform your favorite containers into self-watering pots. Or you can make your own self-watering pots with instructions from websites like these:

Quick and Easy Self-watering Planters
Turn Storage Containers into Self Watering Planters
Video on How to Make a Self-watering Planter

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Self watering planters make growing any potted plant easier. In this post, we’ll explain how they work and answer some common questions. We’ll also show you how to make them, and share tips for using the planters. Don’t have time to make your own? We also list some popular ready made planter options. Let’s get started!

Do Self Watering Planters Really Work?

Yes – but you have to use them correctly.

A “self watering” container doesn’t actually water itself. It is a watering system using planters that contain a reservoir of water at the bottom. This reservoir connects to the area where the plant is with a soil “foot” or a fabric “wick”.

With a soil foot system, the plants send roots down into the foot, and draw up as much water as needed. In a wick system, water is drawn up the wick via capillary action into the soil of the main pot. Either way, if there’s water in the reservoir, the plants have access to water. This allows you water less frequently and still have healthy plants.

When you first fill your planter, make sure the soil is evenly moist. Water from above until plants have a chance to establish a strong root system. With larger containers (especially outside), adding mulch prevents the soil surface from drying out too quickly. This improves planter performance.

After your plant is settled in, simply add water as needed to keep the water level in the reservoir topped off and you should be good to go.

Are Self Watering Planters Good?

I’m a fan! Self watering planters are good for a wide variety of plants – from a vigorously growing tomato plant in a patio garden to petite house plants. Just find the right size and style for your expected plant growth, and you’re set. With a growing interest in urban agriculture, these pots offer a great “first gardening experience” for new growers.

There’s no chance of accidentally drowning a plant, unlike with closed pots or containers that sit in a drip tray. If you accidentally add too much water, it comes out the overflow drain. (You may want to add a drip tray if you have a habit of adding too much water, or set your container outside when you water.)

Are Self Watering Pots Good for Succulents?

Maybe. If you want to use a wicking self-watering container, it’s not a great fit, because they rely on keeping the soil moist. If you want to use a soil foot type, that will work. Just make sure to let it dry out between waterings. It’s also helpful to limit the size of the soil foot to reduce soil moisture. (See below.)

DIY Self Watering Planters

I prefer the soil foot design, so that’s what we’ll cover here. To make your own self watering planter, you need:

  • container(s), such as a plastic storage tub, or set of 5 gallon buckets
  • small basket, pot, or strainer for the soil “foot”
  • watering pipe
  • wood blocks or other supports
  • burlap, mesh or landscape fabric to screen the watering pipe
  • screws and duck tape
  • a drill, a utility knife, and possibly a saw

I found a used storage bin at the thrift store for $3. After the holidays is also a great time to look for deals on containers. You need a container with a lid, or two identical containers to nest one inside the other. Remember, our goal is a built in reservoir under the soil that the plant is in, with a soil foot down into the reservoir.

For the soil foot, we used an old nursery pot with drainage holes, trimmed so that about an inch stuck out above the bottom of the plant chamber. Whatever you choose, make sure it has holes so the water gets in.

Our watering pipe is a 2″ diameter PVC pipe. If you prefer not to use PVC, substitute your tube of choice. The tube diameter needs to be wide enough for you to pour water in.

The video below demonstrates assembly. If video doesn’t load, make sure you are not running an adblocker.

Container Assembly

  1. Cut the lid so it fits snugly inside the container at the width of your blocks. If you use 2×4 lumber on its side, this is 3.5 inches. Next, cut the hole for the soil foot and a spot in one corner for the watering pipe.
  2. Attach wood blocks to the underside of the lid with screws.
  3. Cut watering pipe to fit. Remember, it needs to stick up past the level of soil and mulch. Cover both ends of the pipe with burlap to keep out bugs and soil. (Slip off cover for watering, if needed.) Secure watering pipe into corner with duck tape to hold it in place until you are ready to fill the planter.
  4. Set the lid into place in the bottom of the self-watering container. Fit the pot (or basket) for the soil foot in place. Close any gaps around edges with duck tape or wadded burlap. We want to keep the soil above the lid and in the soil foot, not leaking into the water reservoir.
  5. Drill or punch two drainage holes in the side of the container, just above the level of the reservoir. This allows for drainage in case of overwatering or heavy rains.
  6. Fill the foot with damp soil, packing it in tightly. Fill the rest of the container with good potting soil. Note that most garden soil is too heavy for container plantings, so soil mixes work best.
  7. Plant veggies, flowers or herbs, or a mix, and water well from the top. Top dress with organic fertilizer or compost, if desired. Cover soil with mulch to retain moisture.
  8. Give plants a week or two to get established in their new home by watering from above. Once they are settled in, water using the watering pipe.

Tips for Root Veggies, Potatoes and Other Plants That Prefer Drier Soil

Some plants have more issues with disease problems if the soil is too wet, including root vegetables like carrots and tubers, like potatoes. Succulents kept in wet soil will develop root rot in short order. You can still use a self-watering planter with these plants, but there are a few things you should keep in mind.

  1. Limit the size of the soil foot to 10-15% of the base to reduce water flow to the plants.
  2. Used a lighter soil mix, or add a little sand to your base mix, to limit wicking action.
  3. Allow the reservoir to to dry out between waterings.

Popular Self-Watering Planter Options

From smallest to largest, here are some of the top rated self-watering containers from Amazon.

Lucca Self-Watering Planter, 12-Inch

I have a couple of these planters. They’re light and easy to move, plus you can see the water level via the overflow port. The twelve inch size is great for smaller flowers, herbs or veggies.

Vegetable Planter Box with Trellis

Large enough for several mid sized plants or a combination of short and vining plants. This would make a great patio planter for those with a protected growing area. It includes wheels, so you can relocate if needed without lifting.

CedarCraft Self-Watering Elevated Cedar Planter (23″ X 49″ X 30″)

For those who prefer a raised bed growing system, this CedarCraft self-watering planter is naturally rot resistant and minimizes back and knee strain. It has a 6 gallon reservoir with water level indicator.

Whichever planter you choose, remember that plants like to have at least as much area to grow below ground as above ground. It’s easy to stuff a container too full, and then end up with overcrowded plants as they mature. Our garden planner kit has recommended spacings for common garden vegetables.

What’s Your Favorite Way to Grow in Containers?

I love self watering containers. We used purchased containers for years, but our homemade version is a fraction of the cost and is working just fine. The Swiss chard we planted in it is taking off. With our winds, self watering containers are the best option to keep plants for drying out. They also help keep my houseplants alive when it goes a wee bit too long between waterings. (I confess, we have plants all over the house and I sometimes forget the ones tucked in the out of the way corners.

Do you use container gardening? If so, I’d love to here your stories or tips about what works best for you.

More Gardening Tips

We have over 100 gardening articles on the site, listed and sorted by category on the Common Sense Gardening page. They include:

  • Fresh Food from Small Spaces
  • Small Garden Ideas – 10 Tips to Grow More Food in Less Space
  • How to Start a Garden – 10 Steps to Gardening for Beginners

SIPs:Self-watering Garden, Sub-irrigated Planters

Are you looking to combat severe drought using water conservation in your garden? Do you need to grow in a spot where you have literally NO soil? Or do you just want some really huge vegetables that are easy to grow??? Self-watering (wicking) beds or containers are a great solution. A DIY self watering garden is a water-wise system that will conserve water while growing huge plants!
Gardening with sub-irrigation is the process of watering plants from below the soil line. Through capillary action, the water then slowly rises upwards. For the process to work, the soil (potting mix) cannot be too dense or compact. It must contain air spaces that the water molecules can cling to as they rise. See SOIL for help with the proper ingredients.

How SIPs Work:

Whether you buy one or build your own, it helps to see how a typical self-watering container is made. The diagram below can help you to examine how the various components of an SIP work together:


This demonstrates the basic principles of a DIY self-watering / sub-irrigated container.

The water-reservoir is what makes the SIP such an asset to urban gardeners. Such a planter might be sub-irrigated only. A plastic cover would be placed on top of the soil to hold in moisture & prevent weeds. But if the cover is left off, then the SIP could be top-irrigated in addition to sub-irrigated. If it rains, that rain would be captured. Excess rain would filter down through the potting mix and into the reservoir.
This latter system would mimic (on a small scale) what we see happening everyday on our planet. The surface of the Earth is riddled with massive underground water pockets. This water (known as an Aquifer) consists of permeable rocks that are saturated with water, like a sponge. Aquifers can feed springs, streams, lakes and wells. They can also supply water to plant roots if those roots are near the capillary fringe. The soil in a capillary fringe (which is above the water table) is kept moist by water that travels vertically due to capillary action.


The Earth’s crust is full of Aquifers that act like large-scale SIPs.

Video: SIP Raised Beds
(Watering & Aeration Screen Explanation)

Learn about watering SIPs & how the aeration screen works.

SIPs vs HYDROPONICS? Sub-irrigation is not the same thing as hydroponics. It is not some sort of passive hydro system. Plants grown through “Hydroponics” receive all of their nutrients from a water solution. The soil is inert and provides little more than physical structure. The term “Sub-irrigation” describes a method for delivering water. A hydroponic setup might be sub-irrigated or it could easily be top watered instead. Your SIP system is also hydroponic, if you are feeding your plants with a complete nutrient solution.


The annual veggies in this garden were grown in self-watering containers!

SELF-WATERING? Sub-irrigation or wicking systems are often marketed as “self-watering”. Some people feel this is misleading terminology. To be truly self-watering, the system should store water and automatically add more upon demand. The process works even when you’re away for a time. I’ve seen SIPs that include a float valve which recharges the water reservoir automatically. Such systems truly are self-watering!
Technically a gardener could devise a “self-watering” system that isn’t sub-irrigated. Is a sprinkler or soaker hose considered a self-watering system? What about an electronically controlled ebb & flow set up? Technology has advanced to the point that electronic moisture sensors can send a signal to a computerized water timer which then activates your watering system as needed.
But SIPs are the ideal solution when dealing with containers. The water reservoir is placed directly below the soil container, merging it into a self-contained system. You water the reservoir (sub-irrigation) then the soil or a piece of fabric “wicks” up the water (self-watering) as needed. An air pocket separates the soil and water, allowing the roots to receive oxygen. It might seem complex, but trust me, this is easy gardening!

Sub-irrigated Planter Options:

If you’re in the market for a self-watering, sub-irrigated container, you have 2 initial choices: 1. Buy a retail kit, that has been tested & proven to work. 2. Build your own DIY kit, to the size & specs that best suit your needs. To help you evaluate your options, take some time to examine this chart of SIPs:

SUB-IRRIGATED (SELF-WATERING) PLANTERS
MODEL: EXTERIOR: RESERVIOR: SOIL CAPACITY: DEPTH:
Self-Watering Pat Plntr 26L x 19.75W x 10.5H 4 gallons 10 gallons
Self-Watering Veg Plntr 25.5L x 13.5W x 13.5H 2 gallons 11 gallons 11″
EarthBox (mfr) 29L x 14W x 11H 3 gallons 15 gallons 7.5″
City Pickers (mfr) 20L x 24W x 9.5H 2 gallons 11.2 gallons 6.75″
Garden Patch Grow Box (mfr) 28L x 14W x 12H 4 gallons 9.5 gallons 7 – 8″
30 Gallon Growtainer 30.5L x 20W x 17H 3 gallons 25 gallons 11.5″

Besides price, there are other factors when evaluating a self-watering system:
WHAT IS THE DEPTH OF THE GROWING MEDIA? This will have a large bearing on the types of vegetables you can grow. Don’t expect to grow 8″ carrots in a City Pickers that only gives you 6.75″ of space.
WHAT IS THE SOIL SURFACE AREA OF YOUR SIP? A self-watering container with more surface area, might be a good choice for lettuce, spinach or strawberries.
WHAT IS THE SOIL CAPACITY OR VOLUME? Larger plants like tomatoes will need more growing medium to reach full potential. Also, plants that are heavy feeders may deplete the nutrients too quickly.
Those questions are probably a lot more crucial than the question of water capacity. A 2 gallon reservoir versus a 4 gallon won’t have any impact on the productiveness of your plants. Of course, it might permit you to take a longer vacation without worrying about things drying out. Understandably, a larger reservoir will appeal to those “plant it and forget it” types. However, a vigilant gardener will still want to be outside looking over his or her plants each and every day.

Choosing Your Potting Mix:


This is an example of a typical DIY SIP potting mix. This sample recipe contains Peat Moss Coir Vermiculite Perlite and Pine Bark Mulch.

Your potting mix formulation is absolutely critical if you hope to find success with your sub-irrigated planter. The above chart shows an example of a potting mix that should do well for SIPs. This merely shows the type of components and a basic ratio for mixing them. There are many possibilities. The key is to select base components that are intended for container use as a potting mix. You can start with a retail potting mix and enhance it as desired. Or simply mix your own from scratch.
At one point, EarthBOX had compiled a list of approved mixes. Their recommendation was “a peat-based (70%-80%) growing media that contains perlite or vermiculite. It should be light and fluffy when dry, and spongy when wet. It should NOT contain any rock, clay, or sand. You should also avoid using topsoil or compost.”
The basic idea here is that you’re constructing a mix that will effectively wick moisture to a vertical height of at least 14″ (peat moss or coir). However, that same mix must be porous so as to provide proper aeration to plant roots (perlite or growstones). Also you should have enough drainage for excess rain water to escape down into the water reservoir.
Are you wondering how to fertilize such systems? Should you use compost? Read my multi-page article explaining the ins and outs of fertilizing SIP planters.

← Conventional Containers SIP GARDENING: What to Expect →

After choosing the planter you need to choose the best soil mixture for your planter. You can choose to buy a soil mixture or you can make it yourself. Why do you need to use a soil mixture for planters? The main reason for this is that these mixtures contain additives which are needed to increase the absorption of moisture and retention. Watering planters can also result in a decrease of nutrients in the soil. Adding a soil mixture that contains fertilizers that are released slowly will tackle that problem.

Buy a soil mixture
The following soil mixture can be used in planters that move the moisture upwards through the soil from a built in reservoir.
Container Mix.
Self-Watering Container Mix.
Container Booster Mix.

Make a soil mixture yourself
The most important specifications for soil are that they are light, friable, well drained and moisture-retentive. If you are using normal garden soil you can get diseases and problems with insects in your planter. Here are three well known soil mixtures you can make yourself:

Organic Blend: 5 gallons finished compost, 1 gallon builder’s sand, 1 gallon vermiculite or perlite, 1 cup granular, all-purpose organic fertilizer.
Standard Blend (Cornell Mix): 1 bushel vermiculite, 1 bushel ground sphagnum moss, 8 tablespoons super phosphate, 8 tablespoons ground limestone, 2 cups bone meal.
Light Blend (for rooftops): 5 gallons ground sphagnum moss, 5 gallons vermiculite or perlite, 2 gallons compost, 1 cup granular all-purpose organic fertilizer.

Always use a nutrient rich potting soil for your planters. This potting soil exists of a mixture of coir fiber, compost and vermiculite.

Coir
You can buy coir also in dry bricks. You can soften them with warm water before you use it. The advantage of coir is that it is Leigh weighted, it is easily rewettable and that it does not decompose easily when you mix it. However, the disadvantages are that coir may contain a high salt level and that it does not contain any nutrients.

Vermiculite
You can describe vermiculite as a silicate mineral that consists of thin plates. Vermiculite is heated to a high temperature. The advantages of vermiculite are that it holds water and fertilizer. Another advantage is that it is lightweight and that it allows the roots to breath. The down side is that it can hold too much water resulting in drowning your plants.

A container that waters itself? Almost. The self-watering container (SWC) has a water reservoir that you must keep filled, but other than that, the container and the media work together to provide water continuously over a long period of time.

SWCs can be used to grow a wide variety of vegetables, herbs, perennials, annuals, and small fruits such as strawberries, blackberries or blueberries. They open the door to gardening in places once thought impossible. They can be used on rooftops, patios, balconies, porches, carports, driveways, pool decks, door yards, sunny office windows, city sidewalks, and classrooms. They enable you to garden where there is no garden.

Those with plenty of garden space will also find a place for SWCs. They are a quick and easy way to expand garden space during peak seasons. They can be tucked into areas not currently utilized as garden space, such as along a garage wall or fence line. They can also be used for special applications, such as starting transplants from seed, rooting cuttings, or holding plants temporarily until a permanent location can be decided.

SWC’s are a type of Sub-Irrigated Planter (SIP). They are called sub-irrigated because the water supply comes from the bottom of the media. SWCs and SIPs are popping up everywhere. They are becoming more popular in commercial growing applications, usually where there are tight water restrictions or where soil has been severely damaged from conventional farming methods and extended use of agricultural chemicals.

What are the advantages of using an SWC?

  1. Water savings – The average SWC represents a water savings of 60% over in-ground gardening. If you are under water restrictions, you can still have a bountiful garden; no sprinklers required. Some plants require a constant and consistent supply of moisture to reach peak texture and flavor. It can be tricky to insure this in the garden. Summer heat may mean that the garden has to be watered daily, even bi-daily. Busy people struggle with this. An SWC is uniquely suited to solve this problem. Water is available on demand – the plant’s demand. No more bitter lettuce, no more blossom end rot in tomatoes, no more woody root crops.
  2. Plant health – The soil environment of an SWC is completely in your control. If something you would like to grow has a special soil requirement, such as pH, you can provide that environment in an SWC easily and economically. Soil borne pests and diseases are rare, virtually eliminating the need to use chemical controls. Moisture swings that affect the health and quality of many vegetables are virtually eliminated in SWCs.
  3. Economy – SWCs can be built from recycled components, including containers that might end up in a landfill. Nutrients are never lost to leaching – they stay in the container so none of your dollars wash down the drain into the watershed.
  4. Accessibility – Since most SWCs are above knee height, they can be tended while sitting on a stool or even from a wheelchair. If you thought you had to give up gardening after knee or back surgery, welcome back! The harvest can be a delight; sitting on a stool or “garden scooter” with a pair of scissors in your hand and a basket at your feet, snipping salad greens, plucking tomatoes, pinching herbs, and cutting a few flowers for the table.
  5. Labor savings – SWCs do not require tilling, heavy digging, or frequent weeding, so they are friendly to seniors who miss their gardens, or to school children for their first gardening experience.
  6. Optimize micro-climates – SWCs can be portable, depending on size. You can locate them in sunny areas in the winter, and move them into increasingly shadier areas in the summer to extend your seasons to grow leafy greens and other cool season crops.

Why DIY??
Commercially produced SWCs are available. They can be pricey, and they aren’t always the right size and shape. Many users are concerned that the soil chamber is too shallow for many plants. Building them yourself allows you to design a set of containers that suit your own spaces and needs. The dollars you save making them yourself can be spent on top quality media, organic nutrients, and more plants and seeds!

Don’t worry – it’s easy and requires materials that are widely available and a few common household tools. The SWC we describe below can be built for less than $10 using all new materials, and even less if recycled components are used.

Before we get started, let me say that there are many different methods that can be explored. The following pattern is just one way. We developed this method after seeing over a dozen different DIY SWC patterns, plans, and videos. Our goal was to create something simple and inexpensive. Once you learn the basic principles of how they work, we encourage you to explore other containers and design options that work well for you and with the materials that are readily available in your own neck of the woods.

SWC Basics
The basic components of an SWC are:

  • Water Reservoir/Soil Chamber
  • Aeration Shelf with Supports
  • Mulch Cover Retainer
  • Wicking Pot
  • Fill Tube

All of these will be constructed from common items using a few basic tools. We are going to use an 18-gallon storage tote for this example. They are readily available, inexpensive, and are a great size for many plant choices.

Materials:

  • 18-gallon storage tote with lid
  • 1-gal plastic nursery pot
  • 1.1/2” PVC pipe, 2′ long
  • 1-qt (6″) plastic nursery pots

Tools:

  • Measuring tape
  • Utility knife
  • Drill with ¼” bit
  • Sharpie marker
  • Jig saw (optional)
  • Mitre box (optional)

Building the Aeration Shelf & Mulch Cover Retainer
The Aeration Shelf supports the Soil Chamber and sits above the Water Reservoir, creating an air space between the media (root zone) and the water. This air space provides oxygen to the root zone and prevents the media from becoming over-saturated (waterlogged). The Mulch Cover Retainer keeps a plastic or fiber mulch in place after planting, and provides additional strength to the top rim of the container. Both are made from the lid of the tote.

  1. Snap the lid on the tote. Note that the lid has a lower flat surface we call the “pan” and a raised lip that we call the “rim”. Both are used in our project. Preparing the Aeration Shelf and Mulch Cover Retainer are much easier, and safer, when the lid is in place. It provides some support and keeps hands and fingers out of the way.
  2. Place the 1-gal pot in the center of the lid, upside down.
  3. Use the Sharpie to trace the top perimeter of the pot onto the lid.
  4. Turn the pot right side up and center it inside your previously traced circle.
  5. Use the Sharpie to trace the bottom perimeter of the pot.
  6. Draw a dashed line between the two traced circles, creating a dashed circle.
  7. Decide where you want to locate the Fill Tube (see below). Place the 1.1/2” PVC pipe in that location and trace the outside of the pipe with the Sharpie marker. It should be just slightly larger than the PVC so the pipe slides easily and does not bind up. If you locate it in a corner, as shown here, it will be well out of the way of your plants, and easy to get to when you are filling the reservoir. After you have made your first SWC, you may find that another location is more convenient for you.
  8. Using the drill and ¼” bit, drill a grid of holes about 1” apart each way in the flat surface of the lid. Stay at least 1” away from the center hole and from the start of the rim of the lid.
  9. With the lid still in place, cut out the dashed circle using the utility knife or jig saw. If you are using the jig saw, you must drill a starter hole first.
  10. Cut out the hole for the Fill Tube.
  11. Cut the “pan” of the lid out, leaving the rim intact. You can cut this carefully with a sharp utility knife, or use a jig saw. The location of this cut is different for each tote. It will be at the point where the “pan” of the lid joins the rim. You can find this point by setting the tote on the lid. They are all designed for stacking, with the bottom of the tote sitting on the “pan” and the rim of the lid rising from the outside of the tote bottom. This is an important cut – the Aeration Shelf must fit into the lower portion of the SWC without a lot of space between the shelf and the inside wall.

The now prepared “pan” of the tote lid has become your Aeration Shelf and the rim has become your Mulch Cover Retainer. Set them aside.

Preparing the Water Reservoir/Soil Chamber
This will be made using the main body of the tote. The bottom of the tote will be the Water Reservoir, the top portion of the tote will be the Soil Chamber, and the two will separated by the air space created by setting the Aeration Shelf on top of several supports, then drilling a drainage hole 1″ below the final height of the Aeration Shelf.

For our project, we are using recycled nursery pots as our supports. There are lots of other options – short lengths of PVC, Solo cups with holes punched in them, tin cans with both ends cut out (make sure they are not coated with BPA), reclaimed 1# plastic coffee cans. You will need enough of whatever you use to support the Aeration Shelf and the moist media in the Soil Chamber. It is a good idea to plan to nearly cover the bottom of the reservoir with the exception of the holes we cut for the Wicking Pot and the Fill Tube.

  1. Set one of the supports (pots) beside the body of the tote near where you want to locate the drain hole. This can be any place on the sides or ends of the totes. The consideration is that you should be able to view the drain hole while you are filling the reservoir, and you should have the SWC drain in a convenient direction (for you).
  2. Mark the spot with a dot using the Sharpie marker. This spot should be the level where the “top” of the support meets the side of the container. You may have to tilt the marker slightly to compensate for the diameter of the marker.
  3. Measure and mark a dot 1” below this spot. Drill a ¼” hole at the lower dot. Since most surfaces are not level, it is best to drill more than one drain hole. I usually drill one on each of the opposite sides of the tote. Whichever one is lowest will drain from regular refills, and the other one will help handle any excess rainfall that threatens to drown the tote temporarily.

Making the Wicking Pot
The Wicking Pot is the magic that makes everything work, so we will take time to make sure that we build it correctly. There is more than one way to construct the Wicking Pot, but the principles that make it work must be met.

  • The Wicking Pot must sit on the bottom of the Water Reservoir and reach through the Aeration Shelf into the Soil Chamber.
  • It must have sufficient holes in the base to draw water into the Wicking Media.
  • It must have holes in the sides that will be in the air gap. These holes allow for the air in the media to be displaced during the capillary action that makes the Wicking Pot work.

A 5” Pond Basket meets all of these criteria. A Pond Basket, or Net Pot, is a square, perforated pot made to hold aquatic plants. They are available at many nurseries and big box stores that carry pond supplies. However, a very effective Wicking Pot can be made by recycling a plastic 1-gal nursery container. These pots usually have a bottom hole and often 3 – 4 additional drainage holes, but these are not sufficient for our purposes.

  1. Drill multiple ¼” diameter holes, 1” apart in all directions for the entire height of the pot and all around its circumference.

Note: The 1-gal container we used in this SWC had more bottom drainage than the average nursery pot. It may have been from a succulent nursery. If the walls of the pot are thin, as you see here, go slowly or use a hot nail or the tip of a soldering iron to make all of the holes. There are 8 rows of holes when we finish.

Preparing the Fill Tube
Water must be in the Reservoir at all times. It does not have to be full, but it cannot be allowed to dry out completely at any time. The easiest way to keep the Reservoir filled is with a tube that sits in the reservoir and is filled from the top. This provides constant bottom-up watering and does not wash the nutrients from the media into the reservoir.

The Fill Tube should extend well above the top of the SWC so soil does not fall into the tube. The actual height can be anything that is convenient for the user. I like mine at about 2’ tall because they don’t get lost in the foliage, it is an easy height to fill with a water hose, and it means that I can get (5) Fill Tubes out of one 10’ length of PVC.

If you are only planning to build one or two SWCs, most big box home improvement stores will sell pre-cut lengths. They are a little more expensive than buying it in bulk lengths, but this way you won’t have scrap to deal with.

The Fill Tube should be located on one of the outside edges of the SWC, but it does not matter if it is on the sides or the ends. The location should be the most convenient for watering access.

  1. Cut the desired length of 1.1/2” PVC
  2. Cut the end that will sit in the reservoir at an angle so it will never become blocked (you can also drill several holes in the side of the bottom 2”).

Making the Aeration Shelf Supports
The Aeration Shelf must sit above the top surface of the water in the Reservoir, so it needs something to support it. You can use any number of things for this purpose – 15-oz tin cans, lengths of PVC, quart (6″) nursery containers, even Solo cups.

The parameters are:

  • Strong enough to support the weight of the media.
  • Approximately 4.1/2″ – 5″ tall (for an 18-gallon tote).
  • Allow water to flow into and around them (must have a vent at the top).
  • Numerous enough to keep the Aeration Shelf from sagging.

For this demonstration, we are using quart (6″) nursery pots. We will modify them a bit.

  1. Cut a notch in the rim of the pot. This allows water to flow into the can, preventing it from creating an “air lock” if the rim sits tightly to the bottom floor of the Reservoir.
  2. These pots work to allow water to flow in and around them because there have drainage holes that work as an air vent. If you are using a support that will not vent air from the top, you must drill a vent hole.

Assembling the Components
Now that we have prepared the parts, let’s put them together and start planting!

  1. Set the Water Reservoir/Soil Chamber in its permanent location (they are heavy once filled).
  2. Set all of the Aeration Shelf supports into the bottom.
  3. Set the Aeration Shelf on the supports.
  4. Slide the Wicking Pot into the center hole and check it for fit – it should sit into the hole easily and the bottom should rest on the floor of the Water Reservoir. If it doesn’t sit on the floor, use the utility knife to loosen the hole a bit. Remove the Wicking Pot after checking for fit.
  5. Slide the Fill Tube into its hole.
  6. Snap the Mulch Cover Retainer in place. I find it helpful to use a couple of small binder clips to hold it in place while I work, and later while the SWC is in use.

Fill the Wicking Pot
The media for the Wicking Pot is important – the wrong composition will cause the wicking aspect to fail. This is only for the Wicking Pot. Do not use this as your planting media.

  1. Mix 1 part peat, coir, or peat-based potting mix, 1 part Perlite or Expanded Shale, and 1 part Vermiculite. You will not need large amounts; just enough to fill the Wicking Pot.
  2. Moisten this mix thoroughly. You should be able to squeeze a few drops of water out of the mix.
  3. Fill and pack the Wicking Pot with this media. It should be packed tightly. Leave 1.1/2” of headspace at the top.
  4. Water the filled Wicking Pot until water drains from the bottom.
  5. Fill the headspace with Vermiculite. This should be filled to the point of spillage.
  6. Set the Wicking Pot back into its space in the Aeration Shelf. If possible, mound a little bit of additional damp Vermiculite on the top of the pot, but don’t allow it to spill into the Water Reservoir.

Fill the Soil Chamber
Scoop prepared planting media (see below) into the Soil Chamber until it is 1/3 full. Water thoroughly and lightly tamp it. We do not want to over-pack the media because it is our root environment, we just want to make sure that there are no air pockets in the soil. If you are going to use a dry or pelletized SROF such as Arbor Gate Organic Blend or Microlife, add ½ cup scattered evenly over the media after you wet this layer.

Repeat with the second and last third, again watering thoroughly each time and adding ½ cup SROF. This step is to insure that there are no dry pockets in the media and that it is thoroughly dampened. All surplus water will drain into the Water Reservoir. Starting with thoroughly and evenly dampened media is one of the keys to making SWCs work.

The amount of SROF we are using is a little more than recommended for this volume of soil, but it will be expected to last all season. Do not do this with synthetic fertilizers. Slow release organic fertilizers release over an extended period of time. Synthetics will cause problems. If you are going to liquid feed with something like fish emulsion or Ocean Harvest, you can fertilize in the Water Reservoir later.

Once you have filled the Soil Chamber, mound additional media on the top. This mound increases the root area and creates a drainage mound that will shed surplus rainfall off of the top instead of through the media. Shedding surplus rainfall helps maximize the life of our nutrients.

Applying the Mulch Cover & Planting
The Mulch Cover is used to suppress weeds, to reduce evaporation, and to shed excess rainfall. You can use a black plastic garbage bag or a section of weed mat trimmed to fit. I personally use weed mat. It is porous and allows me to use nutritional drenches if I wish. The Mulch Cover should extend past the rim of the SWC so it can be held in place with the Mulch Cover Retainer. Using the binder clips to hold this all in place is convenient.

To plant through the Mulch Cover, cut X shaped slits in the plastic, pull the cover back, and set the transplant in place or plant your seeds. If you are broadcasting a seed crop or planting closer than 3” spacing, do not use a Mulch Cover. You can mulch with pine straw or compost just as you would an in-ground garden.

Seasonal Maintenance
Taking care of an SWC during the growing season is easy. Just keep the Water Reservoir filled. The media in the SWC will remain damp even in hot weather. The top few inches may feel dry if you are not using a mulch cover, but you will find perfectly damp soil when you insert your finger into the media. If you use a mulch cover, even the top will feel damp.

If you have fertilized before planting, you will not have to side dress during a normal growing season. As always, keep an eye on your plants. They will tell you if they are not happy. If you are using a liquid fertilizer, just mix it in a 5-gallon bucket and use the mix to fill the Water Reservoir. They will self-feed as they draw the mix into the media.

Because you have not used garden soil, you will have few, if any weeds. Any that arrive on the wind or from birds will be easy to prick out from the loose, damp media. Planting can be very intensive in these containers. Close planting also decreases weeds – there is a saying that “where there is a plant there is not a weed”.

After you have harvested a crop, just remove the spent plants, refresh the media with compost and fertilizer, and replant. Coir or peat based media will last for several plantings before it breaks down and needs replacement. Compost based media will continue decomposing, but it does not “break down” in a negative way. It can be used continually with replenishment and fertilization.

How many plantings you get from the media will depend on several things including what type of plants you grow and the environmental conditions in your location. You will need to examine and assess the media between plantings no matter what you choose to use.

Media for SWCs
Media in any container MUST serve four functions:

  • Provide an anchor for the roots.
  • Retain and deliver moisture.
  • Serve as a nutrient pantry.
  • Be an air exchanger.

Media assists in the delivery of water, oxygen, and nutrients. It must retain moisture, but never become waterlogged. It needs sufficient pore space, but no large air pockets or voids. Media is one of your most important decisions, and is no less important in an SWC than it is in other containers or in the garden.

There are several media recipes that can be used in SWCs. Which one you should use will depend on the plants you want to grow, the availability of supplies, and your own personal preferences.

Bagged Potting Mix – Most SWC builders I have encountered use bagged, peat or coir based, soil-free potting mix. This is sufficient for many plants and is available everywhere. You must consider two things – it does not furnish any nutrients (even if it says so on the bag), and it has a tendency to break down over time. There is no reason you cannot use this simple media, but it is not my choice for edibles.

Bagged Potting Mix Improved – Pore space and soil quality can be improved by making modifications to the Bagged Potting Mix. Start with 2-parts bagged, peat or coir based, soil-free potting mix. Add 2-parts Leaf Mold Compost and 1-part Expanded Shale (or Perlite).

I prefer to minimize my use of peat-based mixes. It’s just personal preference. I lean toward one of the two following choices:

The Rose Soil Recipe – You can mix up a very nutritious media by using 2- to 3-parts Rose Soil and 1-part Leaf Mold Compost. This mix is a little heavier than peat or coir based mixes, but it is very friendly to good root development and healthy plants. Rose Soil has compost in it already, but adding more is beneficial, especially for edibles. You can tweak this by adding Expanded Shale or Perlite to increase pore space and lighten up the mix if desired.

I am always experimenting with soils. As long as they meet the basic criteria, feel free to mix and tweak until you find your perfect blend. I prefer a compost based media because it is friendlier to the Soil Food Web – the zone of life in the root zone that is home to beneficial micro- and macro-organisms that aid in healthy plant development.

In my SWCs for tomatoes I use straight two-year old leaf mold compost from Nature’s Way Resources to which I add perlite and vermiculite for aeration and water retention. I pay close attention to nutrition throughout the season. I use SROFs in my soil prep before planting and use nutritional drenches after periods of stress (heavy rains, hot & humid, long duration spring winds).

Arbor Gate Organic Soil Complete – This is a perfectly balanced media right out of the bag. It requires no amendments or tweaking. It is a great media for SWCs.

Notes & FAQs

Depth of Soil Chamber to Depth of Water Reservoir
The SWC works using capillary action. We start with damp media and provide a water source that is in contact with the media through the Wicking Pot. As water is used by the plants or through evaporation, more will be drawn into the media for continual availability. Capillary action has some limitations. The Soil Chamber should be at least 8” deep to be suitable for most plants, but no more than 11” – 12” deep to insure adequate capillary action takes place.

You will need to take some quick measurements when you start a project with a new container. For example, the tote we are using for our project is about 16” deep. We are going to plan for a Soil Chamber that is 11” deep. This means that the supports we will use to hold the Aeration Shelf should be about 5” tall and that our drainage holes should be at about 4” from the bottom if the reservoir to give us the 1” of air space we need. This gives us a pretty significant amount of stored water – approx. 3.3 gallons. A deeper container might mean using taller supports.

Can I put a soil barrier on top of the Aeration Shelf?
Yes, but…..The barrier MUST not block oxygen transfer. You can use a piece of fiberglass window screen, weedmat or burlap. Do not use plastic sheeting. I do not advise using anything at all unless it is an absolute necessity. Roots must breathe. I don’t use anything and I don’t have trouble with soil falling through the shelf. The holes we are using are smaller than the drainage holes on most planting containers.

I cut my Aeration Shelf too small and there are gaps on the sides where soil can fall through. What do I do?

If you cut your Aeration Shelf too small, use a strip of screen among the open edges, not all the way across the shelf. If you cover the top of the media in the Wicking Pot, it will not work.

Some SWC sites recommend laying the fertilizer in a strip on the top of the soil. Should I do that??
I see those, too. I have tried it both ways and I see no advantage of creating a strip of fertilizer in the top of the media. This strip just gets in my way when I plant. Mixing an SROF into the top 2/3 of the media distributes it well and does not interfere with my planting plans.

I see recommendations for using 2 or 3 cups of fertilizer at planting. Should I do that?
I see no reason for this excess, especially if you are using a soil mix using compost and natural nutrients. I use 1.1/2 cups, divided into three portions that I mix into the soil as I fill the container as described above. This is sufficient for a normal season, even for heavy feeders. Your plants will generally signal their needs. If they are growing well, producing as expected, and having few disease or insect attacks, they are telling you they are happy. If any of these signs are negative, you should investigate. The answer might be as simple as a nutrient deficiency, which is usually easy to correct in an SWC.

What containers can I use?
SWCs can be made from many containers – from soda bottles to half of a 55 gallon barrel. Plastic totes are often used because they are not offensive in appearance. 5-gallon buckets recycled from food service companies are also good candidates. The principles are the same for all containers, but adjustments need to be made for wicking. A modified one-gallon pot or a 5″ pond basket is sufficient for an 18-gallon storage tote. In fact, I used the same setup in several 32-gallon totes and they work well.

Can I paint my SWC?
Yes! Plastic containers can be lightly sanded and painted with Fusion paint or Rustoleum 2X. These paints actually bond to the plastic as they cure. After the paint has cured, they can be left as is or decoratively painted. This is a great way to involve the kids, especially if your SWCs are part of a school gardening or science project. It’s also a good way to disguise them from your HOA, if necessary.

What about mosquitoes?

Mosquitoes can enter your SWC through the Fill Tube or the drain holes. Once inside they may breed in the reservoir. This is easily prevented. The drain holes can be covered with a small piece of fiberglass window screen attached with silicone caulk. The Fill Tube can be covered with an inverted can, a PVC cap or plug, or a piece of screen held on with a rubber band or cable tie. The screen does not interfere with filling if you decrease the flow of water a bit.

Improving Wicking
If you feel you are having trouble with wicking, you can modify the Wicking Pot and the Wicking Pot Media as follows:

  1. Mix equal parts coarse Perlite and Vermiculite and moisten the mix.
  2. Fill the Wicking Pot with this 50-50 mix leaving a 1” to 1.1/2”headspace at the top.
  3. Fill the space with moist Vermiculite up to the rim and level off.

There are countless reasons to love a self-watering planter, which is why many of our customers are surprised to learn that not every plant needs one or will even benefit from one.

Water is one of the most important elements in regards to keeping plants alive and healthy. Plants don’t want too much water but they also don’t want too little water, you have to find just the right balance. The world of greenery would certainly be simpler if all plants required the same exact amount of water at all times of the year. Instead, every plant requires a different amount of water, which tends to vary throughout the year.

The latest self-watering planters are made with added qualities that offer true value. Great candidates for self-watering planters include garden vegetables, perennials, annuals and many other popular garden favorites. If you are debating between a self-watering planter and a traditional planter we are here to help you make the best decision for your plants.

How Does A Self-Watering Planter Work?

Humans are always trying to invent ways to make life easier, and self-watering planters do just that. Since all plants need water, what could possibly be more efficient than a planter that waters the plants it holds? Hence why the self-watering planter is so popular.

Self-watering planters are equipped with a bottom chamber that holds excess water, keeping the plant from drowning or experiencing root rot, while also providing additional nutrients for 3-4 weeks.

Nearly all of TerraCast planters can be retrofitted for self-watering capabilities. That’s because we offer a specially made attachment piece that functions as a self-watering system. You can actually add a self-watering system to almost any of our planters, even ones you already have in your possession today. This secondary piece attaches to the bottom of the planter and acts as a water reservoir. It’s super simple to add the additional piece on. If you have any trouble you can always call us for assistance.

The water in this chamber is actually capable of continually feeding your plants. Each of our self-water attachments is equipped with a moisture-wicking system that sucks up moisture from the chamber, redistributing it back into the soil for the plant to absorb.

Plants will never drown because there is an overfill feature that keeps the water reservoir from filling up too much by releasing water out of the side as necessary. Our customers have told us that a 40-60 inch self-watering planter is capable of self-sustaining for as long as a month without needing to be watered again.

When you water your plants, the water falls down through the soil and anything that isn’t soaked up along the way flows into the separated chamber. Thus, you greatly reduce your risk of overwatering your plants and ultimately killing them. If you overwater a traditional planter, the water pools at the bottom of the pot, soaking the roots 24/7. Anything soaked in water for an extended period of time is likely to rot from mold, including the roots of plants.

Does Every Plant Need A Self-Watering Planter?

Self-watering planters are an amazing invention that helps reduce plant maintenance and increase plant health, but that doesn’t mean everyone needs to purchase one. Here’s the thing, self-watering planters are going to cost more than traditional planters because they are more complex and provide added benefits. There’s no need to spend the extra money on self-watering planters if you are not going to receive the full benefits.

If you live in an area that gets a lot of consistent rainfall you don’t necessarily need self-watering planters. In wet climates Mother Nature takes care of the majority of watering, making self-watering planters a bit redundant. Unless, of course, you have issues with root rot because of an extremely moist environment, in which case the overflow system embedded in our self-watering planters will keep the plant from flooding and rotting from the roots up.

Regardless of what the weather is like in your part of the world, if you are going to be placing planters inside they can benefit from self-watering planters; although, weather conditions are not the only thing to take into consideration. The type of plant you are maintaining will also determine if self-watering is right. Plants that prefer an overly moist soil may not do that well with a self-watering planter because the soil will never stay as moist as it would in a traditional planter.

What About DIY Self-Watering Planter?

There are ways to create a DIY self-watering chamber using household items, such as water bottles or rocks. Using the wrong materials to fill a planter could impact the soil in negative ways, backfiring and creating additional issues. There’s no need to try and do it yourself when you can instead get a tried, tested and true self-watering planter that will last for many years, benefiting a vast assortment of plants.

Contact us today to discuss if self-watering planters are right for you!

The 10 Best Self-Watering Planters

Benefits Of Using Self-Watering Planters

Luckily, if you weren’t blessed with a green thumb, self-watering planters make it a breeze to ensure that your photosynthesizing friends get just the right amount of water.

In theory, keeping plants alive seems like it should be easy. Water them, make sure they get plenty of sunlight, and the rest will take care of itself, right? Unfortunately, it’s a bit more complicated than that. Some plants are rather persnickety about how much light and moisture they require to stay healthy, and giving them too much or too little of either can lead to a quick demise. Luckily, if you weren’t blessed with a green thumb, self-watering planters make it a breeze to ensure that your photosynthesizing friends get just the right amount of water.

If you’re the forgetful type, you’ve probably had a plant (or two) die because you simply couldn’t remember to water it on a regular basis. With a self-watering pot, the plant is perched above a reservoir full of water, allowing it to absorb moisture whenever it’s needed. Using the traditional method, some plants need to be watered every couple of days, but depending on the size of the reservoir, you may be able to wait a week or longer before filling it again. This comes in especially handy when you go on vacation or other long trips.

Overwatering is just as bad for plants as not watering them at all. When the soil doesn’t have a chance to dry out, the excess moisture prevents the roots from absorbing oxygen, essentially drowning your plant. The wet environment also provides a perfect breeding ground for certain types of fungi that cause root rot. Self-watering planters help to prevent this problem by watering plants from the bottom, so they only take in as much as they need. This also encourages the roots to grow deep in order to seek out moisture.

In addition to regulating moisture levels, self-watering planters also help to retain the nutrients in the soil. When you water plants from above, nitrogen, phosphorous, and other minerals that plants need to grow will gradually flow out from the drainage holes in the bottom of the container along with the excess water. Thanks to the closed environment of a self-watering planter, those nutrients are captured in the reservoir so that plants can absorb them, meaning you won’t need to add fertilizer as often.

When using self-watering planters, it’s important to choose the right type of potting mix. You want something that’s lightweight and well-aerated so that it can wick moisture to your plants without becoming waterlogged. Heavier mixes, like regular potting soil, are too tightly packed. Soilless, peat-based mixtures tend to work best, and perlite is often added for better aeration. You can buy special mixes that are made for self-watering containers, or make your own to save money.

What Types Of Plants Work Best With Self-Watering Planters?

Some plants can thrive in just about any conditions, even if they’re almost completely neglected. Pothos, Chinese evergreen, and ZZ plants, for example, are extremely hardy and can handle low light and very infrequent watering, so a self-watering planter, while convenient, is not necessary for them. But these tend to be the exception rather than the rule — most plants require a bit more care, and some can be downright picky.

But these tend to be the exception rather than the rule — most plants require a bit more care, and some can be downright picky.

Azaleas, zebra plants, elephant ears, and Ctenanthe plants are very high-maintenance and need a consistent level of moisture, making them perfect candidates for self-watering planters. African violets are also notoriously fussy about their watering needs. They have very shallow root systems that can easily become waterlogged, and self-watering pots are great for preventing their soil from getting too moist.

If you want to try your hand at gardening but don’t have a big enough yard, self-watering planters are great for growing edible plants, as well. Most vegetables, especially the ones that require a lot of water, do very well in them. These include tomatoes, bell peppers, cucumbers, lettuce, potatoes, carrots, celery, broccoli, and cauliflower. They’re also great for herbs that like moist soil, such as parsley, chives, and mint, and you can even buy indoor herb garden kits, many of which are self-watering.

On the other hand, some plants are just not suited for self-watering containers. Cacti and succulents prefer drier conditions than most other plants, and a self-watering pot will not allow them to dry out enough between waterings. The same goes for certain herbs, like basil, oregano, thyme, and rosemary.

Choosing The Best Self-Watering Pot For Your Plant

This may not be true for all things in life, but when it comes to planting containers, size matters. While you certainly don’t want to choose a pot that’s too small and will leave your plant root-bound, too much extra space can cause the soil to hold onto excess moisture, and it doesn’t look very good, either. Shoot for a container that’s two to four inches larger in diameter than your plant, so that it has room to grow without being swallowed up.

It typically isn’t as aesthetically pleasing as other materials, but if you care more about function than form, plastic is a versatile and reliable option.

The material your planter is made of makes a difference, as well. Terra cotta and other clay pots are porous, which can cause the soil to dry out faster, so they aren’t ideal for plants that require a lot of water. Glazed ceramic pots hold in moisture, but the larger sizes can be extremely heavy and difficult to move. Plastic containers are lightweight, nonporous, and inexpensive, and you won’t have to worry about them breaking when the weather gets cold. It typically isn’t as aesthetically pleasing as other materials, but if you care more about function than form, plastic is a versatile and reliable option.

Most self-watering pots are meant for single plants and made to sit on the floor or a shelf, but there are some unique designs out there for less traditional applications. Tiered planters are great for herb gardens and smaller fruits and vegetables. Hanging containers add a decorative touch to your porch or patio and give vines and other sprawling plants plenty of space to grow. Some options even come with a tower or trellis for tomatoes and other plants that grow tall and need some extra support.

Self-watering pots offer convenience, water efficiency, and improved plant health. These pots and planters use wicking action to provide water from a built-in reservoir, allowing you to water your plants by simply topping up the reservoir rather than having to keep track of the moisture level of the soil and watering according to each plant’s particular needs.

How do self-watering pots work? Consisting of a growing bed, potting soil, water reservoir, and wicking system that puts the soil in contact with the water, self-watering pots work through capillary action, or wicking. As the plant roots absorb water, the soil wicks up more, maintaining a consistent level of moisture in the soil.

Sometimes referred to as “sub-irrigation containers,” these self-watering pots have become quite popular because they are very effective and easy to maintain. They’re simple to construct using inexpensive, commonly available materials, or there are many stylish commercial options to choose from.

Although the design possibilities for these self-watering pots are endless, the four basic elements mentioned above always come together to form an elegant solution to houseplant care that’s perfect for today’s busy lifestyles.

Once you understand how these planters work, you’ll see why the self-watering pot trend has exploded onto the scene in recent years. So read on for an in-depth look at how self-watering pots work. You’ll be inspired to give these innovative planters a try.

Capillary Action (Wicking) Explained

The mechanism behind how self-watering pots work is a phenomenon called “capillary action,” or “wicking.” This action is what allows a sponge to draw up liquid from a surface, the hairs of a paintbrush to draw up paint, and the wick of a candle to draw up wax. This is also how plants, including the tallest trees, are able to overcome gravity to draw water up from their roots to the very top of the plant.

Capillary action is caused by the intermolecular attraction in liquids, along with the attractive forces between a liquid and a solid material with narrow tubes or small spaces within it. The attractive force between like molecules that holds a raindrop together is called “cohesion,” while the attractive force between the unlike molecules of a liquid and a solid material is called “adhesion” (think of dewdrops clinging to a flower petal or a leaf).

If the adhesive force between the liquid and the solid is greater than the cohesive force within the liquid, which occurs when the space between the walls of the solid material is sufficiently small, the liquid will be propelled within these spaces.

With self-watering pots, you need to thoroughly water the potting soil from the top at planting. Then, as the plants release water from their leaves, more water is drawn up by capillary action from the plant roots to replace it.

The water that’s absorbed from the soil by the roots is likewise constantly replaced by capillary action within the soil, being fed from the reservoir by the capillary action of the wicking system at the bottom. With the proper potting mixture and wicking mechanism, the soil remains consistently moist but not overly wet.

The Four Basic Elements Of A Self-Watering Pot

Regardless of whether it’s a single-plant pot or a large container garden, there are always four basic elements to these self-watering pots:

Growing Bed

The growing bed is the upper part of the container that holds the potting soil and the plants.

Potting Soil

For a self-watering pot to function properly, it’s important that you use a potting soil that is lightweight and absorbent. It may consist of soil as well as non-soil growing media such as coco coir, perlite, or growstones.

The key is to use something that will continuously wick up water while also providing plenty of oxygen to the plant roots.

Water Reservoir

This essential element of a self-watering pot is located beneath the growing bed. Since you can’t see the reservoir, having a way to monitor the water level, such as a viewing window or a float, will eliminate the need for an overflow outlet for indoor planters.

And of course, there must be a way to refill the reservoir, which can be a vertical pipe for pouring in water from above or an opening at the side of the container.

The two separated areas for the growing bed and the water reservoir may be formed by placing a container at the bottom of the pot, by devising a barrier within the pot, or by having an inner pot for the grow bed and outer pot for the reservoir.

Wicking System

The wicking system is what delivers water from the reservoir to the soil and on to the plant roots. To achieve this, you can either use wicks made of absorbent material such as pieces of rope or strips of cloth that are situated with one end in the water and the other in the soil, or you can devise a wicking pot that puts the potting mixture directly in contact with the water in the reservoir below.

In the next two sections, we will take a closer look at each of these wicking systems.

Self-Watering Pot Wicks

One simple way to bring the water from the reservoir to the potting soil is to use wicks. You can use any kind of absorbent material for the wicks, including cotton, wool, felt, nylon, polyurethane, and microfiber.

However, for long-term use, its best to use a material that is durable and rot resistant, such as the fiberglass wicking that’s made for oil lamps and candle making, which you can find sold in bulk at some gardening suppliers.

When setting up a self-watering pot, you need to make sure that the wicks reach to the bottom of the reservoir so they will always be in contact with the water, even when the water level is low.

At the top end, the wicks should extend into the potting soil rather than sitting on the bottom of the growing bed. To achieve this, simply hold the top ends up when you pour the soil into the container.

The number of wicks you need will depend on factors such as the size of the container, the type of potting mixture, the wicking material, and the number and type of plants.

The general rule is to assume you will need two wicks per plant. However, you should test your wicks out with your soil to find out how well the system functions and be ready to make adjustments if your plants are not having their watering needs.

Wicking Pots

The other wicking system commonly used in self-watering planters is called a “wicking pot.” This describes any self-watering pot design that places the potting soil in direct contact with the water in the reservoir, separated only by a permeable barrier.

Some self-watering pots are actually wicking pots in and of themselves. This is the case with conversion kits that allow you to turn a regular flowerpot into a self-watering wicking pot by inserting a container for water into the bottom of the pot that has a perforated top, which serves as the base of the growing bed.

A wicking pot can also be created by placing a basket filled with potting soil so it extends down from the growing bed into the reservoir. The container needs to allow contact between the soil and the water, so use a basket or some other container with open sections in it. A lining of netting, window screening, or another thin, permeable fabric will hold the soil in.

Another way to create a self-watering wicking pot is to place a layer of gravel or sand in the bottom third of a container that doesn’t have drainage holes, cover it with permeable cloth, and then fill the rest of the container with potting soil.

You can use anything from an old sheet or T-shirt to shade cloth to reusable shopping bags for the cloth barrier. Be sure to insert a section of PVC pipe that will serve as your watering shaft before filling in the soil. You will need to cut a hole in the fabric for this.

What Are The Advantages Of Self-Watering Pots?

There are three major advantages to using these self-watering pots:

  • Convenience
  • Resource efficiency
  • Improved plant health

Now, let’s take a look at each of these advantages.

Convenience

Perhaps the biggest selling point for self-watering pots is that they provide the convenience of simply making sure there is water in the reservoir rather than having to monitor the soil of each potted plant you have in order to supply water when your plants need it.

The task of keeping an eye on each individual planter can be time-consuming, particularly if you have a lot of plants. The watering needs of plants vary according to such factors as the time of year, the weather, the state of the potting soil, the size of the pot, the size of the plant, and the plant’s stage of growth. So when you water according to a weekly schedule instead of according to when the plants actually need it, you run the risk of harming your plants by over- or under-watering.

With self-watering pots, the soil is kept consistently moist, as the water is delivered from the reservoir at the same rate that the plants are using it.

Self-watering pots also offer the convenience of being able to water your plants while you are away from home or are so busy that you don’t have time to attend to your plants properly.

They thus allow people who travel a lot or have very busy lives to enjoy having houseplants without worrying about neglecting them.

Water Efficiency

Another major advantage of using self-watering pots is their water efficiency. These containers systems are self-regulating, delivering water as it is used by the plants. There is a small amount of water loss due to evaporation, but it’s much less than the amount of loss that occurs when you pour water into the potting soil from above – especially if you cover your self-watering potting soil with a layer of mulch.

When you pour water into the top of the potting soil, some of it will evaporate from the surface. In contrast, because self-watering pots draw water from below, there’s less moisture at the surface of the soil and nearly all of the water is used by the plants.

Plant Health

The most common plant care mistake is over-watering, whichcan starve the plant of oxygen and lead to problems caused by fungus and disease, while under-watering deprives plants of the water they need to maintain their cellular structure, transport nutrients, and carry out photosynthesis. Self-watering pots can enhance the health of plants by providing exactly the amount of water they need as they need it.

Self-watering pots also encourage deep, healthy root growth, as the plant roots reach downward for water rather than growing laterally to gather water from near the surface, where the moisture level is highest.

What Are The Disadvantages Of Self-Watering Pots?

Self-watering pots are great for busy people, they’re environment-friendly, and they can enhance plant health – but there are a few disadvantages to these container systems:

  • Self-watering pots are not suitable for all plants: Self-watering pots are not suitable for succulents, orchids, and other plants that need to have their potting soil dry out between waterings. The constant moisture will cause root rot in these types of plants.
  • Self-watering pots don’t function well outdoors in moist or rainy climates: Outdoor self-watering containers will become waterlogged by high humidity and rain. An overflow outlet helps, but it doesn’t prevent the excess water from entering the soil in the first place and causing it to become wet rather than remaining evenly moist.

What Do I Need To Know About Maintaining A Self-Watering Pot?

While self-watering pots are very easy to maintain, there are a few things you need to do to help ensure that your plants are getting the water and nutrients they need.

Fertilizer And Self-Watering Pots

If you are using a hydroponic soilless medium in your self-watering pot, then you will usually need to add nutrients to the water reservoir, regularly maintain this nutrient solution at the proper levels, and flush the growing medium out with fresh water every couple of weeks to avoid the toxic buildup of fertilizer salts.

However, many gardeners prefer to avoid using liquid fertilizers and time-release fertilizers with self-watering pots to prevent salt buildup and instead feed their plants with compost. Flushing out self-watering pots can be tricky with indoor pots that have no overflow outlet.

Be sure include some well-aged sterile compost in your potting soil, and repot with a fresh batch of potting mix each planting season.

If you are using commercial self-watering potting mixture rather than creating your own, the best way to fertilize is to sprinkle a little slow-release fertilizer over the top of the soil before putting your plants in. This allows the fertilizer to slowly make its way down through the growing bed as the plants grow.

Do Not Allow The Reservoir To Dry Out

Self-watering pots are great for people who are always forgetting to water their plants, but you can’t forget to keep the reservoir from emptying because it will cause the wicking system to dry out and it won’t function when you refill the reservoir.

If you do happen to allow the reservoir to dry out, you will need to water from the top, soaking the soil well to ensure that it, along with the wicking system at the bottom of the pot, gets the moisture needed to start carrying out capillary action once again.

What Is The Best Self-Watering Potting Mix?

For a self-watering pot to function properly, it’s essential that you use the right potting soil. You can purchase commercial potting soils that are formulated specifically for self-watering planters. Or, make your own potting mixture with equal parts peat moss, coconut coir, perlite, and good-quality compost.

What Plants Are Best For Self-Watering Pots?

Houseplants that prefer evenly moist soil include smaller, leafy plants such as baby’s tears, spike mosses, and coleus, as well as larger thin-leaved plants such as boston ferns, peace lilies, and umbrella palms. Lettuces, spinach, and herbs also do well in self-watering pots.

What Are Some Of The Commercial Self-Watering Pot Options That Are Available?

There are many commercial offerings available on the market today that provide the convenience of pre-fabricated self-watering pots for your indoor houseplants. They may be stylish self-watering systems such as these:

  • Grobal Self-Watering Flower Pot
  • Santino Self Watering Planter
  • Mkono self-watering planters

Or, they may actually be hydroponic growing systems, like the following:

  • Lechuza Classico
  • LeGrow Self Watering Planter
  • ZeroSoil Planters

And finally, another great option is to purchase a conversion kit that will turn a regular planter into a self-watering system. Here are a few to choose from:

  • Gardener’s Supply Company Self-Watering Pot Reservoir For Planters
  • GroBucket Garden Kit
  • TerraCast Self-Watering Reservoir

Self-Watering Containers

“Self-watering” containers are another option for container gardening. Instead of drainage holes in the bottom, these containers have an overflow hole on one side. The growing medium sits on a perforated platform directly above a water reservoir. Plant roots grow through the medium and into the water. In most cases, water is wicked up from the reservoir into the medium. These containers can be seen as a hybrid between hydroponic gardening (plant roots growing in nutrient-enriched water) and conventional container gardening. Self-watering containers help conserve water and nutrients and make it possible to ignore your containers for a few days.

The simplest application is to place a saucer under a pot. The excess water is wicked up into the media or pulled up by roots that reach the saucer. A number of commercial models are available or you can make your own.

Converting a 5-Gallon Bucket into a Mini-Garden

The ubiquitous five-gallon plastic bucket is considered by some to be the most useful tool on earth, particularly in poor countries. Thousands are buried in landfills or burned each day in the U.S. Thrifty gardeners rescue them from local businesses and use them to harvest, store, and protect crops, carry water and tools, spread compost, and make compost tea. University of Maryland researchers have designed a new use: a mini-garden for vegetables and herbs that recycles water and nutrients and uses only compost as the growing medium.

Materials List

  • 5- gallon plastic bucket and lid (food grade). Bakeries, delis, and restaurants will often give them away.
  • 7.5-inch section of 4-inch diameter perforated drain tile
  • 6-inch section of ½ inch (inside diameter) plastic tubing
  • 1 ½ inch wood or decking screw
  • electrical tape
  • empty 1-gallon milk jug

Tool List

Saber saw, drill, 5/16 inch and 3/4 inch drill bits, utility knife, hacksaw

Construction Steps

  1. Using a saber saw or band saw cut the lid so that it fits inside the bucket. (The lid will separate the medium from the water reservoir).
  2. Drill 15 holes, 5/16” in diameter, in lid. (Plant roots will grow through the medium and pass through these holes into the reservoir.)
  3. With a hacksaw, cut 3 pieces of 4-inch diameter black perforated drain tile 2 ½ inches long. These are placed in the bottom of the bucket to support the lid-separator).
  4. Drill one ¾ inch hole with a drill bit 2 inches above the bottom of the 5-gallon bucket.
  5. Cut a 6-inch piece of ½ inch (inside diameter) clear plastic tubing; wrap one end with electrical tape, to create a snug fit, and insert it into the hole. The tubing will sit directly below the separator.
  6. Drive screw through the tubing (inside the bucket), 1 inch from the end.
  7. Cut an “X” with a knife or razor into the shoulder of a 1-gallon milk jug. Insert the end of the tubing into the milk jug and raise the bucket 8 inches by setting it up on a cinder block or bricks.
  8. Decorate and beautify your bucket with decoupage or spray paint (Krylon Fusion™ for Painting Plastic)

How to Use the “Self-Watering” Bucket Garden

Now that you’ve constructed your mini-garden it’s time to get growing! You’ll be impressed by how easy it is to recycle water and nutrients. Fill your bucket with about 4 gallons of moistened medium, plant your seeds or plants, and add 2-3 gallons of water. The reservoir will fill with water and the excess will travel through the tubing into the milk jug. If it doesn’t rain, your bucket will need to be watered regularly— every day in July and August if it’s in full sun each day. It will take 1-2 quarts of water each day to fill the reservoir. Before adding new water, simply pour back the water that collects in the milk jug. Using this technique no water or nutrients are wasted.

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