- Greenhouse Seed Starting – When To Plant Greenhouse Seeds
- When to Plant Greenhouse Seeds
- Greenhouse Seed Starting
- Seed-Starting Secrets of a Greenhouse Professional
- Seed Starting Guide: Quick Tips for Starting Seeds Successfully
- Seed Starting Guide
- Starting Seeds Without Electricity
- Starting Seeds Indoors
- Starting Seeds Outdoors
- How to Start Vegetable Seeds Indoors
- Indoor Seed Starting
- Finding the Right Growing Medium
- Choosing the Right Container for Indoor Sowing
- How Much Light?
- How Much Warmth Do Seeds Need?
- How Much Water Do Seeds Need?
- How Often Should I Check My Indoor Seeds?
- How to Start a Vegetable Garden: Planting Out
Greenhouse Seed Starting – When To Plant Greenhouse Seeds
While many seeds can be sown directly in the garden in fall or spring and actually grow best from natural weather fluctuations, other seeds are much more finicky and require steady temperatures and a controlled environment to germinate. By starting seeds in a greenhouse, gardeners can provide a stable atmosphere for seeds to germinate and seedlings to grow. Continue reading to learn how to sow seeds in a greenhouse.
When to Plant Greenhouse Seeds
Greenhouses allow you to control the temperature and humidity required for seed propagation and young seedlings to grow. Because of this controlled environment, you can actually start seeds in greenhouses anytime. However, if you are starting plants, which you plan to transplant into gardens outdoors in the spring, then you should start the seeds in greenhouses 6-8 weeks before the last expected frost date for your location.
For best success, most seeds should be germinated in temperatures around 70-80 F. (21-27 C.), with night temperatures that do not dip lower than 50-55 F. (10-13 C.). The temperature in your greenhouse should be carefully monitored. Greenhouses are generally warm during the day, when the sun is shining, but can get much cooler at night. Seedling heat mats can help provide seeds with consistently warm soil temperatures. Greenhouses that are equipped with fans or opening windows can vent greenhouses that have gotten too hot.
Greenhouse Seed Starting
Seeds are usually started in greenhouses in open flat seed trays or individual plug trays. Seeds are prepped according to their specific needs; for example, they may be soaked overnight, scarified or stratified, then planted in trays the greenhouse.
In open flat trays, seeds are usually planted in nicely spaced rows for ease of thinning, watering, fertilizing and treating seedling diseases, such as damping off. Then, when these seedlings produce their first set of true leaves, they are transplanted into individual pots or cells.
In single cell trays, only one or two seeds is planted per cell. Many experts feel that planting in plug trays is better than open trays because the plug cells hold and retain more moisture and warmth for the developing seed. Seedlings can also stay in plug trays longer without their roots becoming intertwined with their neighbors. Seedlings in plugs can simply be popped out and transplanted right into the garden or container arrangements.
When starting seeds in a greenhouse, you don’t need to spend a fortune on special seed starting mixes. You can mix your own general purpose potting mix by adding 1 equal part peat moss, 1 part perlite and 1 part organic material (such as compost).
It is, however, very import that any potting medium you use be sterilized between uses to kill off pathogens that can lead to the seedling disease known as damping off. Also, if temperatures are too cool in the greenhouse, light is not intense enough, or if seedlings are over watered, they may develop leggy, weak stems.
Seed-Starting Secrets of a Greenhouse Professional
We start our seeds in 128 and 288 cell trays both because of the volume of our production and space limitations of our greenhouses. You may be more comfortable using 72 or 128 cell trays. The larger the cells (the cells in a 72-cell tray are substantially larger than the cells in a 288 cell tray) the longer the transplants can be held before they need to be moved.
Our Sowing Technique
We have a vacuum seeder that lets us plant whole trays in seconds, but we also do a fair amount of hand seedling. We fill our trays to the top, level the soil with a brush of our hands, and sow our seeds into dry soil. Instead of covering the seeds with a light layer of soil, a common recommendation, we lightly press each into the soil surface so there is good contact between the seed and the soil. You can see the indentation from the tip of our fingers in the soil surface. You can often still see the seed, pressed into the soil.
The most important additive to initiate germination is water and the most common cause of seed failure is drying out caused by inconsistent watering. After sowing the seeds, we water using a brass seedling nozzle which sprays a fine mist. It takes a while for the soil to absorb the water. We usually make at least three passes at five minute intervals to insure the soil is sufficiently moist. When you pick up an adequately watered tray you will feel the weight of the water.
Cover with Plastic Wrap
For years our planting process ended at the step above. Last year we tried something new with miraculous results. Like many of you, we’d grown accustomed to spotty germination with pepper and eggplant seeds. Unlike many of you, we have a commercial incentive to maximize results so we don’t waste time and space when both are at a premium. Faced with several unsuccessful rounds of peppers early in the season, we decided to experiment by covering our trays with a layer of plastic wrap. Wow, what a difference. Our germination rate increased from an average of 50 percent to 90 percent and sometimes as high as 99 percent. Trays that had previously been spotty were thick with sprouted seeds.
After our trays are sown and covered with plastic wrap, we move them to a professional incubation chamber to initiate the germination process. This chamber is about the size of a refrigerator with trays inside like an oven. At the bottom is a stainless steel basin that we fill with water. Inside the basin there is a water heater element which is controlled by an external thermostat which we usually set at 70 degrees. You may not have a germination chamber, but you should consider trying a location where you can keep your seeds in warmth and in complete darkness for several days. You may find this speeds up the germination process. Our incubation chamber allows us to germinate tomato seeds in three days and pepper and eggplant seeds in 6-7 days. If you don’t have access to a germination chamber, hermetically sealed heat mats that maintain a constant temperature of 70 degrees Fahrenheit are tried and true and make a big difference to success with seeds.
Next time we’ll take a look at how we transplant and care for our seedlings until they’re ready to transplant into the garden. See you in two weeks!
Seed Starting Guide: Quick Tips for Starting Seeds Successfully
Do you struggle to raise seeds successfully? Are you a beginner gardener? Then follow this tutorial on how to be a successful plant ‘parent’. Avoid the most common mistakes when starting seeds.
As a parent, there’s no greater joy than sharing the journey of nurturing a baby from infancy into a healthy young adult. But I confess – I’ve been a bad ‘parent’ many times … Before I learned how to raise my plant ‘babies’ successfully, they starved, drowned, died of thirst or neglect, too much love – or too little! If this sounds like you, then read on for my best tips.
As a gardener, I’m practicing ‘parenting’ skills almost daily raising plant ‘babies’. And boy do I have a BIG family! Babies are being ‘born’ everywhere. In seed raisers, pots and garden beds. Some new additions are planned. Others are not, but they’re all welcomed in my garden.
Over the years I’ve successfully raised thousands of seeds into healthy plants. Like kids, it’s hard to keep an eye on these youngsters. Especially when they insist on entering the world unplanned in some spots in the garden! Being a plant ‘parent’, it’s much easier to raise these babies when you can control where they grow. Then you can keep a close eye on them and care for their needs.
The miracle of seed germination: every seed contains all the food it needs to grow its first 2 true leaves.
“Every gardener knows that under the cloak of winter lies a miracle … a seed waiting to sprout, a bulb opening to the light, a bud straining to unfurl. And the anticipation nurtures our dream.” – Barbara Winkler
Watch this quick clip on the miracle of a seed germinating.
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Seed Starting Guide
Quick Tips for Starting Seeds Successfully
You have three options for sowing seeds:
- In a seed raiser for transplanting later when seedlings are strong enough.
- In a suitable container like a punnet for microgreens or other edibles in a larger planter e.g. poly box.
- Direct sow in a garden bed where you want them to grow permanently.
This video shows you two different methods of sowing seeds – in the ground and into seed trays.
Materials for Starting Seeds
- Viable seeds of your choice. I recommend organic seeds for growing food so you have total control from seed to plate. See Saving and Sourcing Open-Pollinated Seeds for tips and suppliers.
- Clean, hygienic, sterile container with suitable drainage. There are plenty of options for a ‘nursery’. You can buy new. e.g. shallow seed raising flats; cell growing trays; biodegradable jiffy pots; a mini propagator and tubes; or make your own.
You can also make your own seed raisers by repurposing items e.g. plastic punnets, yoghurt tubs or biodegradable toilet rolls.
TIP: Use HOT soapy water to sterilise your container. Especially if reusing pots or seed trays. This is so no soil borne diseases or plant pathogens contaminate your new seeds.
- Growing media or soil-less seed raising mix. NOT commercial potting mix. It can be too coarse for little delicate roots to push through and often contains harsh fertilisers.
- I suggest you make your own seed raising mix like I do. I share five organic recipes in my How to Make Potting Mix at Home Guide.
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- Cover (to create a humid environment). e.g. plastic bag, bottle, mini greenhouse etc.
- Spray bottle or tray with water. No moisture = no germination.
- Light. Preferably natural light or a fluorescent light if raising seeds indoors. Some seeds do need to germinate in darkness, so this is a general rule that can be broken. Check your seed packet for specific instructions!
- Label or plant marker. All babies need names. Many plant families look very alike when young. I once transplanted out what I thought were cucumber seedlings into a raised bed. I went on holidays and returned to find they were zucchinis! They had taken up way too much space because I hadn’t labelled them.
- Patience. Check the days to germination on your seed packet for a guide to how long you have to wait to be a plant ‘parent’!
Starting Seeds at the Right Time
If you’re planning an ‘impending birth’, consider timing. Food crops germinate at specific times of the year depending on your climate zone. Plant in the right season. Ideally, to maximise success, use a moon calendar for optimum timing.
Check your seed packet for the optimum time to plant so you don’t set yourself up for failure.
TIP: “If you have a short growing season, start early. Select seed varieties that grow quickly! Then you need to prepare a space that’s clean, warm and light. With the ‘baby’s’ needs in mind. You can start seeds indoors, in a greenhouse or suitable protected area.”
Like us, Seeds have Basic Needs!
- Air (oxygen in the soil).
- Moisture (to soften the coat of the seed and form roots).
- Warmth (some seeds won’t grow if the soil is too hot or cold).
Seed Raising Mix
Use a good quality mix for starting seeds. It should be:
- have good drainage
- moisture holding capacity
- sterile and free from pathogens (soil borne diseases).
You can buy a commercial mix or make your own seed raising mix. Garden soil is NOT recommended. It compacts easily and may harbour diseases.
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7 Basic Steps to Starting Seeds
1. Always check your seed packet for specific directions. e.g. To sow direct or into a seed raiser first. The most suitable season and depth to sow. Soil temperature and spacing. Whether the seed needs light, darkness or pre-soaking.
2. Spread your seed raising mix firmly into your container. Tap down to remove air pockets.
3. Make sure your seeds have good contact with the soil. They need moisture to germinate. Small seeds or those that need light can just lie on top of the seed raising mix. As a general rule for larger seeds, sieve extra seed raising mix evenly over the seed to a depth of twice the seed diameter and moisten well.
4. Put your seed container in a protected warm position. e.g. on top of a hot water heater or use a heat mat underneath to increase the soil temperature. Keep your seeds in a humid environment until they germinate. You can add a cloche or close the lid on your mini greenhouse. Alternatively cover with a plastic bag or film. (Remove this once the seeds have sprouted).
5. Make sure there’s consistent moisture once the seeds are in their ‘bed’. Too dry = no germination. Too wet = seed can rot/die. Just right = you’ll be the proud parent of new babies! Check daily. Use a spray bottle to finely mist water over the seeds. Or add your container/tray to a shallow water bath with warm water. This allows moisture to wick up into the seed raising mix without disturbing your seeds. Remove your container when the mix feels moist.
TIP: A moisture meter is a very helpful tool.
6. Label your seeds and be patient. Not all babies are born on time! Check the seed packet for a guideline to the number of days to germination so you have a ‘due date’.
7. Feed your babies! Once the seed baby is ‘born’, it will quickly grow its first 2 true leaves. At this point your plant baby will have used up all the nutrients inside the seed. It will be totally reliant on YOU for food to grow. A weekly liquid feed is ideal to get your little one thriving. Try a weak solution of seaweed (kelp) or worm ‘juice’ (liquid from a worm farm).
Successful Seedlings – Out in The Big Wide World…
If you’ve started seeds indoors, you will need to ‘harden them off’ for a week or two before transplanting outdoors. This helps them acclimatize. Think of it like this. You are giving your seedlings short little ‘day trips’ (for a few hours). This helps expose them to sheltered conditions to toughen them up a bit without them getting stressed!
Hardening off pumpkin seedlings before transplanting
From then on, your youngsters are very vulnerable until they grow strong enough to go out into the big wide world and fend for themselves. There are plenty of things that can go wrong. They can starve. Get too hot or cold. Drown or feel thirsty. Get gobbled by hungry insects or animals looking for a free feast. Become weak and leggy. Plus a host of other hazards! So put your ‘protective parent hat’ on until they’re able to safely ‘move house’.
If you have sowed edible seeds directly in the garden, thin them out. Keep only the strongest plants. Eat the rest as microgreens, packed with enzymes and flavour.
Healthy seedlings ready for planting
Just like us, our plant babies need love and attention. If they get a healthy start early in life, they generally grow into healthy productive plants that reward us for a job well done. So, get sowing!
For more tips on sowing seeds, dig into:
- 5 Mistakes to Avoid when Raising Seeds
- How to Prevent and Fix Leggy Seedlings
- Easy Guide to Growing Microgreens
- 12 Valuable Tips to Grow Healthy Microgreens
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After months of planning and dreaming about our gardens, the longer days of February are a great time to get an early start growing spring and summer vegetables, herbs, and flowers.
Often, advice on how to start seeds involves equipment such as heat mats and grow lights. While it’s true that such equipment may lead to more reliable germination and sturdy growth, setting up lights and heat mats may not be feasible for every gardener.
The cost of purchasing mats and lights, and running round-the-clock electricity to the equipment can be prohibitive. And homesteaders like us who live off-grid and use solar power for electricity may not generate enough power in the winter months for such a seed-starting set-up.
Starting Seeds Without Electricity
Without the benefits of an electric heat mat or grow lights, I had to come up with creative electricity-free ways to start seeds, both indoors, and outdoors.
Here are a few ways to start seeds without electricity. I’d love to hear which method you like best!
Starting Seeds Indoors
With a sunny south-facing window, and plenty of space, starting seeds indoors without the use of grow lights or heat mats is possible – it just requires a little more attention.
Seeds will germinate in different areas of your home, depending on their specific temperature requirements. Place cool season crops in flats in your basement or root cellar; for warmer season crops, germinate seeds near a wood stove or other heat source. Some people like to use clear plastic domes or plastic wrap to retain moisture until seeds germinate. Remove this cover as soon as seeds germinate.
When seeds have sprouted, move flats to the sunniest location in your home, preferably a south facing window. I like to rotate my flats at least once a day, to ensure that plants are getting even light on all sides.
When days have warmed up, consider moving seedlings to a cold frame outdoors to get more direct sun exposure and to begin the hardening off process.
Starting Seeds Outdoors
Have you noticed how some hardy varieties reseed and germinate in the outdoors with no intervention? Often these plants lead to the first harvest. Such is the concept behind the winter sow method. Using the winter sow method, seeds are sown outdoors in the dead of winter, in a simple, homemade micro-greenhouse -namely recycled plastic containers!
Here’s how it works:
First, to select successful winter sow varieties, look for plants that have been selected for cold-climates or that require cool temperatures for germination. Think “Red Russian” or “Siberian” kale, “Winter Density” lettuce, or “Giant Winter” spinach.
Next, gather plastic containers that have tight-fitting lids. Takeout containers with a clear-plastic lid, organic washed salad green boxes, salad bar containers, or even plastic milk jugs are great choices for winter sowing. Put a few drainage holes in the bottom of the container, fill with a nice well-draining, organic soil to about an inch below the top, sow seeds according to directions, and give them a good drink of water.
Label your containers, and then turn your attention to the clear plastic lid. The lid needs ventilation, so as to not bake the tiny seedlings. Poke several slits in the lid, and then put the lid on tightly.
Now set your micro-greenhouses outside (yes, outside in the snow and cold!). They will freeze and thaw, and freeze again, and that’s okay! On a day when the sun is shining, and the air is warm, check the containers for moisture levels, adding water if needed.
As your seedlings grow, cut larger and larger slits in the cover until more of the lid is open than not. Before long, you will have fully hardened-off seedlings, ready to plant into the ground. No heat mat, no grow lights, no taking up valuable windowsill space!
Another useful tool for those wishing to get a jump-start on their spring or summer gardens are cold frames. Cold frames, which are low boxes outfitted with a clear glass or plastic lid, are easy to make, can be constructed with reclaimed materials, and are a low-cost and small-scale substitute for a hoop house or greenhouse.
Cold frames protect small plants from the elements, and heat up the soil when the sun shines. As such, cold frames can benefit seed-starting gardeners in two ways: as a place to direct sow seeds, or as a place to harden off seeds started indoors. Consider direct sowing arugula, beets, spinach, lettuce, or radish directly into well-composted organic soil. Or transfer your growing seedlings from the indoors into an outdoor cold frame when the days warm.
One note of caution: Since they are typically oriented to the sun, cold frames can heat up quickly. On sunny days, be sure to ventilate your cold frame so your carefully sowed seedlings do not fry in the sun!
If you are blessed with a climate that allows you to direct sow in the early spring, do so! As soon as the ground is dry enough to work, and the soil is warm enough for the types of seeds you would like to plant, direct sow them right into the ground, following recommendations for that particular variety.
My intrepid (Zone 5) neighbor will even broadcast very cold hardy greens such as lettuce or mache directly on top of a snowy garden bed! As the snow melts, the small seeds work their way into the ground, germinating when conditions are right.
Although I have used low tunnels in the past to help tomato and other warm season plants get a head start in a cold spring, these days I’m using low tunnels to grow food year round. As I harvest food (kale and spinach are what I’m growing this year), I sow a few seeds in the empty space. So far, I’ve sprinkled corn salad, spinach, and kale in the low tunnel, and am watching for germination!
Whichever method you choose, getting a jump-start on your spring or summer garden does not have to be an expensive, equipment-intensive process. Start your seeds without electricity, indoors or outdoors, and you’re on your way to a successful harvest!
For a step-by-step guide to growing food year round, check out my Fall Gardening Guide!
How to Start Vegetable Seeds Indoors
Purchase your seeds from a trusted source. Fresher, higher quality seeds will have a higher germination rate (meaning more will sprout), and will give you a head-start in growing delicious, nutritious vegetables. (Check out Landreth Seed, our line of heritage and heirloom vegetable seeds!)
Pot with seed-starting mix. These mixes don’t contain any actual soil, but they provide ideal conditions for sprouting seeds. Most importantly, they provide a good balance of drainage and water-holding capacity, and they minimize problems with disease on vulnerable seedlings. If possible, don’t use garden soil to start seeds indoors; it generally doesn’t drain well and may contain plant disease spores.
Make sure your containers have drainage holes. You can use recycled pots — for example, empty yogurt containers — but be sure to poke holes in the bottom for draining, so that your seeds are not over-watered. Plastic six-packs and flats are good choices and can be reused year after year. Biodegradable pots are fine, too.
Plant seeds at the proper depth. Check the seed packet for planting depth. You don’t need to measure precisely, but be careful not to plant any deeper than the directions suggest. The rule of thumb is to plant the seed two-to-three times as deep as the seed is wide. For example, tiny seeds should be barely covered by soil mix, while large seeds like beans should be sown about an inch deep. If you sow seeds too deeply, they won’t have enough stored energy to make it to the surface. Plant extra seeds, because it’s likely not all of them will germinate; you’ll thin out the extra ones later.
After sowing, set the containers in a warm location. On top of the refrigerator or near a radiator are usually good spots. Check your pots every day for signs of growth!
Keep seed-starting mix moist. Seedling roots need both air and water. Strive to keep the mix moist but not saturated with water — think of it as a damp sponge that contains both water and air.
As soon as seedlings emerge, place pots in a bright location. A sunny window will do, but adding consistent light from supplemental fluorescent lights will give you the best results. Suspend the lights just an inch or two over the tops of the plants.
Cool room temperature is best for seedlings. You’ll get sturdier, stockier seedlings if you grow them at temperatures in the high 60s. Finding a cooler room in your house or garage, while still maintaining a good light sorce, will help them thrive. At higher temperatures, seedlings may get leggy.
Begin fertilizing weekly. Use a half-strength fertilizer once your seedlings have one or two sets of leaves. Organic fertilizers are a good choice, since they provide a range of nutrients, including micronutrients.
Once seedlings have two sets of leaves, it’s time to thin. You want one seedling per pot, so choose the healthiest, strongest-looking seedling to keep. Snip the other seedlings off at the soil line and discard them.
Are you looking for unique, heirloom vegetables known for generations of successful growth? Check out Landreth Seeds, Scrupulously Selected Since 1784! You’ll find more than 100 vegetable varieties to try in your garden this year.
Shop Vegetable Seeds
Indoor Seed Starting
It’s possible to have a fine vegetable garden by buying young plants, but you will have a much wider range of possibilities if you start your own plants from seeds indoors. Not only is it much cheaper, but you can buy seeds for many more varieties than you will find for sale as plants. This will allow you to experiment with more different flavors, shapes and colors, and to harvest your favorite edibles over a longer period by planting varieties that mature at different times.
Why is it necessary to start some plants before it’s warm outdoors? Many of our favorite flowers and vegetables, including tomatoes, peppers, squash and beans, are native to such places as Central America and Mexico, where they had many more hours of sunlight in their growing season, and a much longer season of warm temperatures than they can get in most of the United States. Their seeds will not sprout in soil that is still cool in spring and the fruits need more sun to ripen than is available in the waning days of autumn. If you were to sow tomato seeds in the ground outdoors in May in New England, Oklahoma or Minnesota, the plants would take so long to grow that the first frost in October would likely kill them before you got a single ripe tomato.
Even for crops that don’t come from near the equator, starting seeds indoors gives some plants a head start that brings earlier harvests and greater yield. The same is true for many of our favorite annual flowers. If you start them indoors, they can spend more time in your garden flowering instead of maturing enough to flower. Even many perennials benefit from a good head start indoors.
Note that not all plants should be started indoors, some are best sown directly in the garden (see this article on direct-sowing seeds). Different plants have different needs, so always refer to the directions on the seed packet to tell you when and how to sow your seeds.
For your first experience of starting seeds, it’s wise not to take on too much. Start no more than a couple of dozen plants in three or four varieties while you learn how it all works. Starting seeds is not complicated or difficult, if you understand the process. The basic ingredients are a proper growing medium, containers, light, warmth, water and your attention.
Seed Starting Introduction
Finding the Right Growing Medium
Seedlings are very delicate. For the best chance of success, start them in a fresh, sterile seed-starting mix that is light and fluffy and designed to hold just enough moisture. If the growing medium is too wet or not sterile, disease can strike. If it is too heavy or sticky, fine new roots won’t be able to push through it.
Burpee offers a range of seed starting soils, from compressed coir pellets (coconut husk fibers) that expand when wet, to bags of loose seed starting formula. All our mixes have a trace of starter fertilizer in them so you will not need to start fertilizing until the seedlings have several sets of leaves.
Choosing the Right Container for Indoor Sowing
Anything that will hold the growing medium and has drainage holes will work, but we recommend specially designed seed starting kits because they include everything you need to grow strong, healthy seedlings. Burpee offers a variety of seed starting kits that include trays with cells, expandable coir pellets, a tray to set them on and a clear lid to hold in humidity during the early stages.
An alternative to using the kits is to purchase biodegradable pots that break down in the soil. You can plant them right in the garden and so avoid disturbing the young plant’s roots. Some are shaped from organic wood fiber or peat, or you can make your own from newspaper. Don’t confuse these with biodegradable resin pots; those will break down in a landfill or, eventually, in a compost heap, but you can’t plant them directly in the garden. Burpee offers a range of fiber pots and a kit for making pots from newspaper.
How Much Light?
Seedlings need lots of light or they will be spindly and feeble. A very sunny, south-facing window may do just the thing for a handful of plants if you are not too far north, but artificial plant lights can ensure that your plants will get the light they need even on cloudy days and during those shorter winter days. Burpee offers a range of lighting options for gardening from platinum LED lights that you mount from the ceiling to light carts with LED or T-8 light bulbs, to our smallest tabletop Ultimate Grow Light with CFL bulb. All these lights have the broad spectrum range of light rays needed by plants. They are adjustable in height so you can raise them as your seedlings grow.
A timer can be helpful to turn the lights on and off so the plants get the 16 hours of light they need every day, and a good rest at night. You want to keep the lights just 3 to 4 inches above the plants.
How Much Warmth Do Seeds Need?
Seed-starting happens in two stages: germination and growing. Germination is the sprouting stage, when the root and leaves emerge from the seed. You won’t need light at this stage because it occurs under the soil, but you will need gentle warmth (not harsh heat). You can provide heat by using special heat mats available from Burpee in a range of sizes to fit your seed starting needs. These will keep your seedlings about 10 degrees F warmer than the air temperature, allowing the seeds to germinate faster, leading to healthier seedlings. Once you see green sprouts about half an inch tall, you need the plant lights. You can remove the heat mats as long as the room temperature is between 60 and 70 degrees F.
How Much Water Do Seeds Need?
Plants consist mostly of water to keep them turgid, and they need it for the photosynthesis that gives them energy to grow. Water is also what starts the germination process. But while water is essential for plant growth, overwatering is the most common cause of seedling failure.
Sow your seeds in an evenly pre-moistened mix. It should be moist but not soaking wet. Cover the container to hold in humidity while the seeds germinate with the cover from your kit, or a clear plastic wrap. Try to allow for some air circulation, however. Burpee’s seed starting kit lids are designed to fit loosely on the top of the try to ensure some air circulation.
Once they sprout, uncover the containers and water them from the bottom by pouring water into the tray. Make sure air circulates freely so humidity isn’t trapped around plants.
How Often Should I Check My Indoor Seeds?
This is the secret ingredient to successful seed-starting: you should check your seeds daily. Check to see if the seeds have sprouted so you can remove the cover when it’s time and make sure the seedlings have light; check to make sure they stay properly moist but not too wet; check your reservoir if you have a self-watering kit; check the seedlings’ growth and raise the lights so they stay 3-4” above the plants; and check to make sure the lights and timer haven’t malfunctioned. If you are starting a few seeds on the windowsill, turn the plants every day so they don’t bend toward the light.
As you plan your seed starting, factor in your convenience and habits. Will you really remember to check seeds in the basement daily? It might be wiser to start seeds in the guest room or kitchen where they will be handier, even if you have space for fewer seedlings.
As your seedlings grow, watch the weather. Although a few crops can go outside earlier (refer to the seed packet), most should stay indoors until after the last frost date for your area has passed and your soil has warmed. If your area is having a cold spring, hold off. Gardeners are always eager, but many a carefully nurtured tomato seedling has been killed by a May frost or simply slowed down by cold soil. Protect your investment of time and attention by planting later rather than earlier.
Finally, introduce your plants to the sun gradually, a process called “hardening off”. Expose them to sunlight for one hour more each day for a week. During this time bring them to a protected location outside when they are not in the sunlight. If there will be a frost at night, bring them inside. After a week or so, they will have acclimated to the outdoors and will be ready to transplant.
How to Start a Vegetable Garden: Planting Out
So you’re wondering how to start a vegetable or kitchen garden? Not to worry. Our seven-video series, “How to Start a Vegetable Garden,” will help you get your first veggie venture off to a good start. We’ll cover the basics: choosing a location, preparing the soil, building raised beds, starting your seedlings, and planting your garden. This video is about planting out.
7. Planting Out
Planting out is simple, but there’s more to it than just digging a hole and tossing the plants in the ground. Here are some steps you can take to ensure healthy, hearty plants.
Step 1: Harden off your seedlings
If you’re planting homegrown seedlings, you’ll need to make sure your plants are hardened off. Hardening off is the process of acclimating your plants to the harsh conditions of the outdoors–getting them used to the heat, cold, wind, and sun.
Put your seedlings outdoors in a protected location for an hour a day for about a week. Gradually increase their exposure until your young plants have adapted to the temperature fluctuations that they’ll face outdoors. If you have plants from a nursery, always make sure to ask if they’ve been hardened off before you plant them.
Step 2: Dig a hole
Your hole should be as deep as the plant is in its container, and at least twice as wide. Digging a wide hole helps with soil aeration and ensures that the plant’s roots will be able to spread.
Step 3: Tease the roots
If your plant is in a peat pot, first peel away the peat. Peat takes too long to break down and wicks moisture away from the plant’s roots. If your plant is in any other kind of container, just pop the plant out of it. Use your fingers to loosen up the plant’s roots (don’ t be afraid to rough them up a little), especially if they are very dense or the plant looks rootbound.
Step 4: Put the plant in the ground
Place your plant in the ground at the same level it was in the pot. Then backfill around the plant. Push it snugly into the ground, but don’t compact the soil too much.
Step 5: Water
Watering gets your plants off to a good start and helps to remove air pockets from the soil. Don’t be alarmed if your wilts and looks miserable for a while. Plant go through transplant shock. It’s normal, and watering well will help them settle in nicely.
Step 6: Mulch
Many people prefer straw for the vegetable garden because it breaks down quickly and can be cultivated into your beds at the end of the season, but any organic material will do. Hay should be avoided as it incorporates the seed pod at the top of the grass stalk, which means you’ll have even more weeds to contend with.
Pile mulch around your plants 2 to 3 inches deep and keep it away from the crown of the plants so you don’t suffocate them.
See more videos in this series:
2. Testing Your Soil
3. Removing Sod and Vegetation
4. Building Raised Beds
5. Starting Seeds Indoors
6. Direct Sowing Vegetable Seeds
7. Planting Out
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