Best mulch for gardens

Contents

What is the Best Mulch? Benefits and Drawbacks of Various Mulch Materials

Colored wood mulch is often made from recycled wood that can contain objectionable additives—including arsenic from pressure-treated wood—and is not always 100% hardwood. Pressure-treated wood containing arsenic was phased out a decade ago by the EPA, but old crates and pallets may still be entering the recycling stream. If you’reconsidering colored mulch, be sure the manufacturer uses raw lumber rather than recycled wood. The dyes used for colored mulches are considered safe, however.

(Whenever using wood mulch products, never let it contact any wooden siding or other parts of your home. Termites can and do inhabit wood mulches, but it’s not necessarily a reason to avoid wood mulches altogether. Termites will take advantage of increased soil moisture provided by any mulch for shelter.)

Compost and manure used as mulch add large amounts of organic material to the soil quickly, improving soil structure and nutrient and water holding capacity. However,they do not inhibit weed growth nearly as well as wood or needle mulches. If you use your own compost to mulch, be sure you have not put any material that had herbicides in your mulch bin.

Rarely used alone, landscape fabric or weed barrier is usually covered with other mulches for aesthetic reasons. While the double-barrier is excellent for stopping weeds, using fabric barrier with mulch keeps desirable organic material from reaching the soil as the organic mulch on top breaks down. Eventually this creates a layer of “dirt” on top of the fabric which needs to be removed periodically. Weeds can and do develop in this dirt layer and can be difficult to remove if they root through the fabric into the soil below.

Still relatively uncommon due to its expense, shredded rubber mulch does not breakdown and can be considered nearly permanent. The color remains stable for many years and it stays put better than almost any other mulch. It is, however,very heavy and difficult to move, and adds no beneficial organic material tothe soil. Rubber mulch can also have a disagreeable odor that can persist for a while after installation. It is ideal for playground areas as it won’t cause splinters and absorbs impact from falls.

In the right setting, stone mulches (pebbles, gravel or rocks) can be a good choice. They stay put and don’t break down. Smaller sizes such as gravel and pebbles can eventually sink into the soil, requiring touch-up applications (this is where landscape fabric is best used-under stone mulches to prevent sinking) . Larger sized rock mulches can make it difficult to add plants and are difficult to move or remove if you change your mind. Stone mulches can be less effective in reducing water loss from soil when used in sunny areas-the rocks keep soil warmer, increasing evaporation.

There are several products that should never be used as mulch: sawdust, wood shavings and un-aged wood chips. As these materials begin to break down, they consume large amounts of nitrogen, depriving surrounding plants of this vital nutrient. Commercially produced wood products intended for mulch have been aged past this stage and are safe to apply around plants.

What’s The Best Natural Mulch For My Garden?

Spring is coming and it’s time to start thinking about mulching your flower beds for the summer. Natural mulch is extremely beneficial for a garden. It traps moisture in the soil so you don’t have to water as often, and it acts as an insulator so your plants’ roots don’t get too hot. (It has the same insulating effect in the winter, keeping plants from getting too cold.) And it suppresses weeds, so you don’t have to weed as often!

What is the Best Natural Mulch?

There are a number of natural mulches out there, with hardwood bark mulch, pine straw and old hay most popular. Which is the best choice for your garden?

Using pine straw mulch

Pine straw is good for suppressing weeds. It has a tendency to form a thick mat, and woe to the weed that tries to come up through that! But pine straw is not for every garden. Over time it can turn your soil acidic and make it difficult to grow anything. Some plants love acid soil. If your flower bed is primarily made up of these acid-loving plants, then pine straw is not only okay, it’s perfect.

Using hardwood bark mulch

Most people’s gardens grow plants that prefer their soil neutral to sweet (alkaline). Hardwood bark mulch is the best for those plants. It decomposes into a rich, sweet-smelling black dirt, and it looks ever so tidy while doing it. Plus, hardwood bark mulch is the best for amending your soil. The problem is, it’s expensive, especially when you’re buying it from a garden center at a dollar seventeen a bag (and they’re not big bags, either).

Using hay as a natural mulch

Old hay, on the other hand, is dirt cheap. If hay gets wet and spoils, farmers can’t use it to feed their animals anymore; it might kill them. For a gardener, however, that spoiled hay is exactly what your garden needs. In fact, your garden will probably like it better than the fresh, unspoiled stuff and your vegetable garden will probably like it better than the hardwood bark mulch, and you can often get an entire bale of spoiled hay for just a couple of bucks.

The problem with old hay, of course, is that hay is made from grass (or grains). Grass in a garden is a weed, and that hay is just chock full of the seeds of its kind, plus some other weeds that may have gotten bundled up with it. What’s a gardener to do?

In her ought-to-be famous “No Work Garden Book,” Ruth Stout has a very simple solution for what to do–just add more hay. Hay piled around plants to a depth of about a foot (30 cm.) is too thick for weeds–even its own weeds, to get through. It’s a great solution for the vegetable beds (and it really does work).

For the flower beds, however, it has the unfortunate effect of making them look untidy, and an untidy flower bed might just as well be full of weeds.

So then, what is the best natural mulch choice?

What’s the best solution for the gardener? In general, for the flower beds, go with a simple bark mulch. It isn’t as good as hardwood bark mulch, but it isn’t as expensive either. Spread it 4 to 6 inches (10-15 cm.) thick around your flowers, making sure to cover the whole bed.

For the back garden and the vegetable garden, go find a farmer and buy up as much of his old, spoiled hay as you can afford. Spread it 8 to 10 inches (20-25 cm.) at first; increase it to a foot (30 cm.) if some intrepid weeds start poking their heads out (but be sure to pull the weeds out, or they’ll just keep going like the proverbial beanstalk).

Ideally, gardens should be mulched twice a year–once in the spring and once in the fall. It’s not an exact science: when it starts to feel warm, mulch your garden; when it starts to feel cool, mulch your garden.

Mulch has many benefits for your garden. What are you waiting for? Start mulching!

Here are five types of mulch to consider:

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Compost
Use your compost as mulch. Simply spread it around the garden, applying it up to 40mm deep. Compost has great evaporation control and is good for adding humus to the soil. It is more expensive than other forms of mulch, however this is a great option if you have a compost bin and only have a small area to mulch.

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Pea straw
Pea straw mulch is ideal for roses, flowers, vegetable gardens, trees, shrubs and fruit trees. This type of mulch stimulates growth and insulates roots from weather extremes. It does break down quickly and will need to be topped up on a regular basis. It is high in nitrogen, so pea straw mulch is ideal for poor soils. Pea straw is generally sold in bales, is easy to handle and transport.

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Sugar cane mulch
Sugar cane mulch is made from dried sugar cane leaves and tops and is sold in bales. It is less expensive than other mulches, easy to handle and more readily available. This type of mulch breaks down quickly, encourages soil organisms and is good for vegetable gardens. Top it up regularly.

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Barks and woodchips

These type of mulches take longer to break down so it’s more economical, as you don’t have to apply it as often. Barks and chips are best used around established plants like shrubs and trees where immediate soil improvement is not required. Wood-based mulch can cause nitrogen deficiency, which causes plant leaves to turn yellow. This can be overcome by adding blood and bone, which adds extra nitrogen to the soil

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Pebbles and gravels
If you want to go a long-lasting mulch, pebbles and gravels work well. This includes products such as scoria, gravel and stone river pebbles This type of mulch is best suited to succulents and Mediterranean-type plants like lavender. It won’t improve the soil structure, but it will help reduce soil evaporation.

How much mulch you should apply, depends on the type of mulch you use. As a guide, you should apply between 2 and 6 centimetres of coarse mulch. Straw mulch can be applied thicker.

What is the Best Mulch for Vegetable Gardens?

One hallmark of any healthy garden is the effective use of mulch. Mulches help control weeds, prevent disease, conserve moisture, maintain consistent soil temperatures, enrich the soil and make the garden look good. And, a well-mulched garden can produce more vegetables than an unmulched garden due to its ability to reduce foliage and disease. But the effects of mulch aren’t all good. The variety of mulch you choose and the benefit you desire will play an important role. Here are some differences in the types of mulch and their attributes for your vegetable plants.

Pros/Cons of Mulching Your Vegetable Garden

Like all applications of mulch, it is an individual choice. Organic vs inorganic. Cheap vs expensive. Clay vs sand soil. What looks good versus what doesn’t. And the list can go on. What are some factors that should be considered when deciding whether to use mulch?

In many cases, the potential problems of having mulch are inferior to the benefits of mulch. Plus, there are numerous options to prevent any issues that arise when mulch is used.

Mulches for Vegetable Gardens

Organic Mulches

Organic mulches come from plant materials such as bark, leaves or needles, grass clippings, or compost. Here are some considerations for your vegetable garden.

Grass Clippings

It is best to use dry grass and build up that layer gradually to a few inches thick. Using a thick layer of green grass will give off excessive heat and foul odors rather than decompose like other organic materials. Grass clippings decompose rapidly and provide a dose of nitrogen to the growing plants. It is best to avoid clippings from lawns that have been treated with herbicides or fertilizers.

Hay or Straw

Hay and straw are clean, light, and they break down relatively easy, giving your plants more of what they need to grow. Avoid products that are full of weed seeds that will later sprout in your garden. Since straw and hay will compost pretty quickly, check the depth after about six weeks as you will probably need to add 2 or 3 inches to help keep the weeds down and moisture in the soil.

Pine Needles

If you are looking to raise acidity levels in your garden soil, using pine needles as mulch is a great option. During heavy rain, pine needles tend to stay put and do not wash away making them a great choice for sloped gardens. Needles breakdown slower than other organic mulch options and they turn a silver/gray color as they age.

Leaves

A 2 to 3-inch layer of leaves will provide good weed control and decompose fairly quickly. Easy to get, leaves will improve the soil by releasing nutrients during the decomposing process. Leaves that have been mowed or run through some other type of shredder will remain in place longer than unshredded leaves, and they will decompose faster, as well.

Bark & Wood Chips

Probably the most common type of mulch, bark and wood chips come in various varieties and colors. As bark and wood chips break down, the organic matter gets worked down into the soil through the activity of earthworms and insects that live and burrow in the soil. This enriches the soil and leads to healthier plant growth. Bark and wood chips do break down quickly and will need to be replenished periodically to provide weed suppression and water conservation benefits.

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Primarily composed of discarded yard and kitchen waste, the rotten trash of decomposed organic ingredients is a prized substance for gardeners. Using compost as a mulch will provide your plants with rich nutrients over a long period of time. As rain falls on the compost, nitrogen and carbon are worked into the soil providing high-quality amendments. Over time, composting materials will revive the soil and vanquish any toxins that would prevent plants from growing and thriving.

Inorganic Mulches

These man-made materials also work well for vegetable gardens.

Black Plastic

If you abhor weeds, one layer of black plastic will help with weed management. Over time the plastic will be broken down by sunlight and must be replaced. It will increase the soil temperature and this should be monitored so that plant roots are not damaged. Often, an organic mulch is applied on top of black plastic to absorb sunlight and prevent overheating of the soil.

Landscape Fabric

Like black plastic, landscape fabric slows weed growth. This product is great under stones and gravel as it will keep rocks from sinking into the soil. It also makes removal of rocks and gravel easier if you decide to change up your landscaping plans. Landscape fabric makes weeding very difficult and is not recommended under organic mulches. It is better to let organic mulches decompose and mix into the soil.

Newspaper

Using newspaper will provide good weed control. Readily available, newspaper will decompose after one season and can also be used to keep plants from encroaching beyond their desired location. To keep newspaper in place, it is best to water it down and cover it with an organic mulch or soil. The newspaper layer will biodegrade into the soil allowing roots to penetrate and moisture and soil microbes to pass through.

What is the best mulch for vegetable gardens?

It comes down to the gardener’s crop and personal preferences. Organic gardeners will rely on organic mulches due to their natural ingredients and availability. This isn’t to say that inorganic mulch is bad, but it is best to avoid mulches that don’t integrate with the soil and reduce the fertile composition of the garden bed.

The best vegetable garden mulch is the one that works best for your plants and soil. If you want something that decomposes quickly and introduces nutrients over time, wood chips are a good choice. If you need to make your soil more acidic, pine needles will work best. Mulch for vegetable gardens shouldn’t be complex or expensive, but each option has its attributes and drawbacks. Keep it simple and see what you like as you find your perfect mulch.

Mulching trees and shrubs

Mulching plants is both functional and decorative. Mulch typically is an organic material spread on the soil surface to protect roots from heat, cold, and drought, and to provide nutrients to plants as it decomposes. Once you have chosen the right plant for a given site, and followed the proper planting procedures, you should mulch the plant and create a stable environment for root growth.

MULCH MATERIAL

What makes good mulch? Several factors should be considered when choosing mulch:

Texture. Medium-textured mulch is best. Fine particles tend to pack down and retain moisture, which then evaporates before reaching plant roots. Coarse-textured materials may be too porous to hold adequate amounts of water.

Nutrient value. Organic mulch provides nutrient- rich humus as it decomposes. This also improves soil structure.

Availability. Consider the availability of different mulch material and whether you have to haul it yourself. Bulk materials may be available free from your community.

Aesthetics. The type of mulch used is a personal preference. Choose for yourself the look you desire. The Morton Arboretum uses organic mulches because of their many plant benefits. Ideally, organic mulch should be composted or otherwise treated before use so that weed seeds, insects, and disease microorganisms are killed. Composted mulch generally has more uniform texture than mulch that is not composted. Composting is probably not needed for disease and insect control if the mulch is derived from healthy plants; however, if it has been sitting outside indefinitely it is likely that weed seeds are present.

TYPES OF ORGANIC MULCH

Grass Clippings. Dry or compost before using. Mix with other materials to increase porosity and reduce matting. A source for some nitrogen but also higher alkalinity, which may compromise nutrition.

Hardwood Bark. Pine bark or shredded bark, can be purchased as bags of small or large chips. Long-lasting.

Hardwood Chips. Readily available and often free from municipal sources.

Composted Leaf Litter (leaf mold). A good source of nutrients but may increase weeds if not thoroughly composted.

Animal Manure. A good source of nutrients. Compost before applying or plant damage (burn) may result due to high salt content. Ideally, should be mixed with a coarse-textured material.

Mushroom compost. A good source of nutrients when mixed with soil or other materials. Source of large amounts of alkalinity and sometimes salts.

Peat Moss. Compacts easily due to fine texture and dries out quickly, best mixed with soil and other materials. Not recommended as a top dressing because water will not penetrate when dry.

Pine Boughs. This is a good covering for perennials in the winter.

Pine Needles. Not widely available and should be mixed with other materials unless soil acidity is desired.

Sawdust. Compost first or mix with a nitrogen source (manure and/or fertilizer) before applying. Oak sawdust helps acidify soil and is good for azaleas, rhododendrons, and blueberries. Do not use sawdust from treated lumber.

Sewage Sludge. A good source of nutrients. Composted sludge is available commercially (i.e., Milorganite or Nutricomp) and should be incorporated with soil or mixed with other composted material.

Shredded Leaves. Leaves are variable in texture and can be collected and shredded at home. Mix into the soil in the fall and allow to break down naturally during the winter for improved soil quality.

Straw. Coarse-textured so it persists a long time, but can blow away easily unless mixed with other materials. Generally not suitable as a landscape mulch, but provides winter protection and cover for grass seed.

APPLYING MULCH

Spread mulch under trees, shrubs, and throughout planting beds to a recommended depth of 3-4 inches for medium to coarsetextured materials.

Pull mulch away from the bases of tree and shrub trunks creating a donut-hole (image on left.)Do not pile it up against the trunk (“volcano mulching”). Excessive mulch on the trunk causes moisture to build up, creating ideal conditions for insect pests, diseases, and decay (image on right.)

Ideally, the mulched area around a tree should extend to the drip line of the branches, or at least cover a 4-5 foot diameter area around the trunk. The larger the mulched area, the more beneficial.

Check the mulch depth annually and replenish as necessary.

Correct mulching on left, incorrect mulching on right

BENEFITS OF MULCH

Provides an insulation layer. Mulched soils are warmer in winter and cooler in summer than bare soils. Roots are protected from temperature extremes, creating less freezing and thawing of the soil in winter, which can heave and injure plants.

Conserves soil moisture. Bare soil surfaces heat-up in summer, causing water evaporation and sometimes root desiccation and death. A layer of mulch reduces moisture loss by preventing sunlight from reaching and heating the soil. Mulch also insulates the soil moisture from evaporation by wind. Less watering is required during high summer temperatures.

Improve the soil’s physical structure and fertility. As mulch breaks down it adds humus to the soil, increasing organic matter in the surface of heavy clay soils and improves the water holding capacity of light, sandy soils, and slowly releasing nitrogen and phosphorous into the soil.

Prevents erosion and water runoff. Bare soil disperses or breaks apart when impacted by rain or sprinkler droplets. Mulch protects soil from being eroded and reduces water runoff by providing a “sponge” surface that absorbs water and slows it down.

Reduces root competition. In the Midwest, most of a tree’s fine roots are in the upper 12- 18 inches of soil. Applying mulch under trees and shrubs eliminates competition from other plants for water and nutrients. Turf roots are especially aggressive and pose the largest threat of competition to trees and shrubs. Create a “living” mulch by using plants that are more compatible with tree roots: bulbs, wildflowers, ferns, ground covers, and other herbaceous perennials.

Additional benefits of mulch include

protection from lawnmower damage

recycles yard/landscape waste

provides a more natural appearance of the landscape

provides a favorable environment for earth worms and other organisms that benefit soil structure and fertility.

POTENTIAL DISADVANTAGES OF MULCH

Problems may arise if mulch is used incorrectly. Too much mulch can be harmful. Consider the following points to make an informed choice and avoid problems:

Creates a barrier to oxygen and water. Plastic mulch or weed barriers prevent oxygen and water from penetrating the soil and should not be used unless they are porous.

Excessive moisture. Fine-textured mulch, such as peat moss, grass clippings, and sawdust, holds a lot of moisture and should be used only in mixtures with other coarser materials.

Heat injury. Dark-colored mulches absorb heat during the day and lose heat at night as surrounding air temperatures fall. This heat may sometimes injure succulent plant tissue.

Root collar rot. Excessive mulch mounded around the base of a tree can cause decay of the vital tissue at the root collar. Once decayed, serious disease organisms may more readily enter the plant.

Soil temperatures. If applying mulch as winter protection, avoid applying it too early in the fall, since mulch can delay the soil freezing process by retaining heat in the soil. Furthermore, if applied too early in the spring, mulch can inhibit soil warming and delay root growth. As a general rule: wait until after a hard frost in the fall to apply winter mulch, and after the last frost in spring to apply summer mulch..

Weed seeds. Some types of organic mulch (e.g., straw, hay, manure, and some leaf litter mold) may harbor weed seeds and should be composted or otherwise treated before use so that weed seeds are eliminated.

Mulching plants

About mulching

Many different materials can be used to cover the soil’s surface, including bark chippings, leaf mould, well-rotted farmyard manure or crushed shells.

Mulching has many benefits. It can provide nutrients for plants, lock in moisture, form a barrier against weeds and can help to insulate the roots of vulnerable plants from winter cold. Mulches can also be used for decorating the tops of pots.

What to do

When to mulch

  • In the autumn, spread a ring of mulch around newly planted trees, shrubs or herbaceous perennials. In early winter, tender plants like Verbena bonariensis or dahlias will benefit from a thick mulch. It will help protect roots and the crown of the plant from frost.
  • The best time to mulch entire beds or borders is in late-winter or early spring. This will trap in moisture from wet weather and ensure beds don’t dry out quickly in the heat of summer.

How to mulch

  • Before mulching make sure the site is clear of weeds and the soil is moist. Water if necessary as it’s difficult to wet dry soil through a layer of mulch.
  • Fill up a wheelbarrow with your chosen mulch and spread a 5cm (2in) layer around plants or across the soil with a spade, leaving a little gap around the stems of plants.
  • Rake to a level finish.

Watch video

In this video Alys Fowler uses home-made compost as a mulch.

Types of mulch

  • Well-rotted manure can be bought from garden centres or in bulk from farms and stables. In the fruit or vegetable garden it provides plants with nutrients as it decomposes. Wear gloves when handling and apply to borders in spring.

  • Bark looks good and improves soil as it rots down. It’s sold in different grades, which differ in ornamental appearance and the speed they break down in the soil. Generally, the finer the material, the quicker it rots.
  • Cocoa shell is ideal for flowerbeds. Wear gloves and water well after laying – this lets the shells bind together. Avoid if you’re a dog owner – its strong chocolately smell is irresistible to pooches, but will upset their stomachs.
  • Gravel and grit are great around tricky alpine plants. The coarse material will prevent rotting at the base, as the rain will run straight through it.
  • Grass clippings can be used around plants in summer, but they don’t look attractive so use at the back of the border or under large shrubs. If you have treated the grass with weed killer do not use the clippings for at least four cuts.
  • Chopped organic wheat straw is perfect for using in large areas and makes a long lasting layer that adds organic matter back to the soil. Wear gloves when handling.
  • Crushed CDs, tumbled glass, polished pebbles and crushed shells are decorative mulches for small areas and are best used in the tops of pots.

Mulch is the term for any organic material used as top dressings on your garden beds. The top dressing could be compost mulch, bark mulch, sawdust, shredded leaves, pine needles, grass clippings, straw hay, etc.

Landscapers use mulches for several reasons:

  1. During the growing season mulch discourages weeds to grow, conserves moisture in the soil, and helps maintain soil temperatures.

  2. During the winter mulch provides protection for perennials, roses and other sensitive plant material.

  3. Mulches enhance the beauty of garden beds with texture and color to complement the plant material.

Compost Mulch is made out of organic material. Use 1 to 3 inches of compost in vegetable gardens, flower and shrub beds. At the end of a growing season, compost can also be added to annual flowerbeds to improve the soil for future growth.

In general:

  • Mulch can be applied any time of year; however, the best time is mid-spring when the soil has warmed. If applied earlier, the soil temperature will stay low and plant growth might be delayed.

  • Typically mulch should be applied 2 to 4 inches deep over relatively clean, weed-free soils. Covering existing weeds will not control them. If you have a weed problem, you can install weed barriers such as newspaper, weed fabric, or black plastic before applying mulches.

  • Water soil deeply before applying mulch; never apply mulches to dry soil.

  • When selecting mulch, think about availability, affordability, appearance and simplicity of maintenance.

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