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How to Grow Seedlings

Are you starting the seedlings and don’t know where to start. Today I’ll share with you all the steps and our tips and tricks on How to Grow Seedlings indoors successfully.

Variety of plants in small containers on the grass.

updated post from March 2013

HOW TO GROW SEEDLINGS INDOORS

It’s really hard to beat the freshness and taste of vegetables grown in your own garden. Eating a ripe tomato straight off the plant is nothing short of amazing. Slice it up, season it with salt and layer it onto a buttered piece of bread. For me fresh veggies are a must during the summer months. I use our abundant crop to prepare canned soups, pickled veggies and meals for the freezer to enjoy throughout the year.

To grow seedlings inside you need: moisture, warmth and light and a drop of patience.

A man inserting a bamboo stick into a seedling for support.

SEEDS

You can pick vegetable seeds at local nurseries. However they don’t often have specialty seeds and for that reason we often order online.

OUR FAVORITE VEGETABLE SEEDS AND PLANT VARIETIES (coming soon)

  • Tomato Seeds
  • String Beans
  • Zucchini
  • Cucumber
  • Peppers
  • Carrots
  • Radishes
  • Cauliflower
  • Broccoli
  • Lettuce
  • Peas

HOW LONG DO SEEDS LAST?

Depending on the vegetable (onion seeds don’t last more than one year) seeds when stored properly can be viable for several years. How to store seeds? Store seeds in an airtight container, in a cool and dry place. Most important is to keep them away from the moisture as the can rot. You can freeze or refrigerate seeds as well. Use plastic bags or glass jars.

Blue bucket with packets of seeds inside of plastic bags..

SOIL FOR SEEDLINGS

It’s best to use a potting soil designed for growing seedlings. You can also prepare your own potting soil. It’s important to note if the soil has a fertilizer or not. If it doesn’t you may need to feed your small plants after seeds germinate with a very light fertilizer. Too much fertilizer can burn the plants.

TIP : Before you start your seedlings bring the soil indoors or into a heated room so it’s not too cold when you plant the seeds.

Spray pressure bottle and garden soil in a bag.

CONTAINERS

When we first started our vegetable garden we used really small seedling containers (as you’ll see in some of the pictures). They are so dainty and take up very little space. But we didn’t find them to be very efficient.

Instead, we use larger containers, preferably at least 1/2 quart to 1 quart containers (3-4 inches in diameter). We use yogurt containers that I wash and save in a gardening bin in the garage. Before we pour soil into the yogurt containers we also drill couple of holes in the bottom of the pot. This is very important for a good drainage.

  • Why we use 3-4 inch diameter pots for seedlings?
  • With more soil in the container soil doesn’t dry out so quickly.
  • Seedlings grown in 1 quart containers are stronger.
  • Large and more resilient plants.
  • Well established roots, roots are not so tangled up.
  • Plants were easier to harden off and and transplant into the garden.  

TIP : We put containers into large bins. It serves 2 purposes : soil doesn’t get spilled onto the floor and established plants are easier to move outside to harden off. To protect the walls from accidental soil spillage we cover them with a plastic sheet that is used for painting. You can get it in the paint department at your local hardware store.

Many containers filled with soil under light.

WATER AND FERTILIZER

Seeds need moisture to germinate. You don’t want them to be swimming in a pool of water and you also don’t want them to be planted in a dry soil. After you plant the seeds into the moist soil remember to water the soil again.

Don’t use cold water. Use lukewarm to warm water and in case your soil hasn’t warmed up yet use hot water to water. It’s okay. Then check every day if the soil is moist. It shouldn’t be wet or seeds can rot. But also don’t let it become completely dry.

To water we like to use a pressure spray bottle, as we can easily control the pressure or use the mist setting as needed. Be gentle when you are watering, don’t just pour water into the container. If your containers are small soil will dry out quickly that’s also another reason why we prefer larger containers to grow our seedlings.

HOW TO SPEED UP GERMINATION?

Soak the seeds in hot water for up to 24 hours prior planting. Don’t soak them for longer as they could rot. Be sure to bring the soil you are using inside 1-2 days before planting to warm it up.

Seedling containers under the work clamp lights.

WARMTH

For the seeds to germinate they need moisture and warmth. Moisture you can provide with water. Warmth you can provide with either heat germination pads/mats. Or you can place your containers by a heater, a radiator or in a well heated room. Some people place their seedling on top of the fridge.

We keep our containers in a well heated room with a wood stove running.

LIGHT

Once the seeds germinate providing sufficient light is essential for growth. As soon as your seeds germinate and you spot those 1st set of leaves (it’s so exciting, I know!) you need to ensure there is enough light for your little plants to grown. Without adequate light your seedlings will die.

To provide light we use work clamp lights fitted with daylight bulbs. We have them clamped onto a 2 by 4 wood piece that sits on 2 chair, one chair on each side. You can also you day light LED lights.

Containers with soil and clamp lights above them.

HOW TO PLANT A SEED?

Pour loosed up soil into containers, water it generously with warm water. Make a hole in the soil, about 1/2 to 3/4 inch deep. Plant 2 seeds to 1/2 to 3/4 inch deep into the moist soil. Loosely cover seeds with soil.

  • TIPS AND TRICKS
  • Don’t plant seeds too deep into the soil, 1/2 inch to 3/4 inch is good.
  • Plant seeds into the warmed up soil. Bring the soil indoors several days before planting to ensure it’s not freezing cold.
  • Before you plant the seed into the soil, water soil with warm water.
  • Speed up germination by soaking seeds in hot water for up 24 hours but not longer, as they can rot.
  • Place containers with planed seeds in a warm spot or a well heated room. Use heat pad if necessary.
  • Wait for the seeds to germinate. Don’t fertilize plants at this stage.
  • Check soil every day to ensure it’s moist. Water seedlings with lukewarm water until 1st leaves emerge.
  • In case both seeds take, wait a few days to see if they both survive and then pull the weaker one out.
Small pot with soil.

HOW LONG IT TAKES FOR SEEDS TO GERMINATE

Germination time can take several days and up to several weeks. For example peppers can take anywhere from 7-21 days. During this stage warmth and moisture is very important so the seeds can germinate.

  • TIPS AND TRICKS
  • Don’t over water soil, seeds can rot if they stand in water.
  • Use a heating pad or place your starting seedlings into a heated room, Many of the seeds required constant warmth.
  • Check the soil daily to unsure it’s moist.
  • Don’t just pour water in, be mindful, we use pressure water bottle. Sometimes misting is all you need too keep your germinating seeds happy.

When the seed germinates you’ll see seed leaves emerging from the soil. Yay, this is always so exciting! As soon as you see the 1st set of leaves bring in the lights or place seedlings in a well-lit spot.

1st seed leaves don’t look like mature foliage of the vegetable plant. They all look very plain, smooth and nearly identical. However, 2nd set of leaves will look different and you’ll be able differentiate vegetable plants just based on the leaves.

Small pot with freshly sprouted seed with seed leaves.

After the 1st set of leaves called cotyledon (seed leaves) watch for more leaves to start coming out. 2nd set of leaves is referred to as “true leaves”. Seed leaves will eventually fall off, this is normal.

Small pots with soils and green seedlings.

TIP : To make sure you know which plant is what it’s best to label each container with the name of the vegetable or type of the seed.

Small seedlings with seed leaves in containers.

We usually group same vegetable seedlings onto the same tray or into plastic containers. Bellow, we grouped Aruba Peppers into one bin.

Medium size vegetable seedlings in containers with soil.

USING ARTIFICAL LIGHTING TO GROW SEEDLINGS

To ensure young plants have sufficient light we use artificial light. We use clamp work lights fitted with daylight bulbs. You can also use LED lights to provide adequate light for your plants.

Containers filled with soil with work lights above.

Process of growing vegetable seedling from a seed to an actual plant takes several weeks. During this time you need to provide sufficient moisture, light and warmth to your young plants. You may also feed your seedlings with a mild fertilizer. But don’t feed them before seeds germinate.

When plants grow too tall support them bamboo sticks and a garden tape.

Established seedlings in containers under lights.

IS IT BETTER TO PLANT SEEDS OR SEEDLINGS INTO THE GARDEN?

Some vegetable seeds are better to planted directly into the garden. Such vegetables include : peas, radishes, onions.

IS IT WORTH STARTING VEGETABLE SEEDLINGS

Seeds are usually cheaper than seedlings. Growing your own seedlings also gives you freedom to try different varieties of vegetables. Nurseries only carry so many different varieties of different vegetable plants.

From our experience when we bought seedlings at nurseries we often brought home garden pests like beetles. And in addition when the plant had some disease it would spread on other plants, too. That being said we shop plenty at a local, family owned nursery for some of the seedlings and herbs. Just be sure to check the plants for pests and that they are disease free.

HOW TO HARDEN OFF SEEDLINGS

Before you transplant your established vegetable seedlings into the outdoor garden it is important to harden them off. This is an important step, don’t skip it.

  • Start hardening off plants for at least 1 to 2 weeks before transplanting them into an outdoor garden. We prefer to harden them off slowly, for 2 weeks.
  • It’s important to allow plants to adjust to a new environment, temperature changes, wind and direct sun. This process takes a little bit of time and it shouldn’t be rushed.
  • Start by taking your seedlings outside on a nice day into a sheltered location. Late mornings and early afternoons work great.
Seedlings in small pot in a large plastic bin on a port table.
  • Don’t place seedlings into the direct sunlight, use a shady location.
  • Don’t place seedlings into the windy spot, shelter them. Either put them into a tall box or place them in a spot that is not so windy.
  • Under a tree is a good spot, too.
  • Water plants well before you take them out, soil may dry out faster than normally causing them to wilt slightly.
Containers with seedlings on a green grass.
  • Leave young plants outside for 1 hour for 2-3 days, then increase time to 2 hours and each day add one more hour up to 7-8 hours.
Pepper and tomato seedling in a large plastic bin on a porch table.
  • Leave them outside couple of days for 7-8 hours. Gradually introduce them to direct sunlight.
  • Don’t forget to bring plants inside every day until they are ready to be transplanted into the garden.
Pepper seedlings in large containers on a terrace table.

WHEN TO PLANT VEGETABLES INTO THE GARDEN

When you plant vegetables into the garden depends on a type of a vegetable you are planting (cold weather or warm weather) and your planting zone – for recommended planting dates check the USDA Hardiness Zone Map.

We are in the zone 6b and we plant cold weather vegetables in early Spring, these plants are not bothered by the mild frost. And warm weather vegetables we plant usually mid-may, after danger of frost.

TIP : Start the seedlings 6-8 weeks indoors before you plan on transplanting them into the garden.

COLD WEATHER VEGETABLES

Cold weather vegetables are vegetables that can withstand cold temperature. They actually thrive in cooler temperatures. They are best planted early spring and fall. And they usually go to seed when it gets too warm for them.

Here are some of our favorite cold weather vegetables we grow in the garden: beets, carrots, peas, lettuce, scallions, broccoli, radishes, kohlrabi, spinach, cauliflowers, brussels sprouts, cabbage, arugula, kale, garlic. Potatoes can also be planted early; it is best when they are sprouted as it will take a very long time for them to sprout in a cold soil.

WARM WEATHER VEGETABLES

These vegetables thrive in warm weather, they don’t do well in cold temperatures.

Here are our favorite warm weather vegetables or fruits we grow in the garden : tomatoes, peppers, zucchini, cucumbers, beans, spaghetti squash, butternut squash, watermelon, strawberries, potatoes, sweet potatoes.

It’s always a good idea to watch the forecast and if there is a risk of frost it’s better to take measures to protect warm weather vegetables. Learn how to protect vegetable plants from late-spring frost.

TRANSPLANT SEEDLINGS INTO THE GARDEN

Prepare your garden, may it be raised bed garden, containers, or ground level garden. Fill the garden space with soil. Learn more about How to Build a raised bed garden and how to prepare for a new season.

If this is not your first year growing vegetable garden, it’s important to prepare garden for a new season. Start by turning soil in the garden either manually with a gardening shovel or use a handy rototiller. Don’t skip on plowing your garden. Churning the soil helps to aerate it, it breaks up large chunks of soil for better drainage and root growth and it’s easier to plant seedlings and seeds.

With a garden trowel make the holes in the soil or in a potting container if you are growing vegetables in the containers. If you are short on space you can definitely use containers; we’ve done that our 1st year and it works.

TIP : When using containers, make sure there is a good drainage.

Man making a hole in the soil with a small shovel.

If the soil is dry, water it well and allow water to soak into the soil, (steps 1-4).

Pouring water into a hole in the soil.

Turn the container with a young plant upside down and gently wiggle it out, (steps 1-2)

Gently tore the tangled up roots, (steps 3-5).

Hand holding a seedling and gently breaking up tangled up roots.

Push the plant roots down into the hole. Press it firmly down, (steps1-3). Cover it with more soil and push it down again, (steps 4-6). Then water the plant again.

TIP : Pour water around the stem, don’t pour directly on the stem.

Hands placing a seedling into a hole in the soil and firmly pressing it down.

COMMON PROBLEMS WITH SEEDLINGS AND HOW TO FIX THEM

  • Seeds are not germinating – soil is too cold, seeds were planted too deep, not enough water or warmth, old seeds
  • Yellow, brown leaves on seedlings – too much water, too cold
  • Main stems are too thin and leggy – not enough light or seedlings are overcrowded, competing for light
  • Seedlings wilted and died off after transplanting – plant was weak, not properly hardened off
  • Brown Edges and leaves with spots – most likely Spider Mites – use a mild solution of Nuke Em spray, or Neem Oil or try Insectidical Soap. (be sure to test on couple of seedlings first before treating the whole batch)
Sprouted seed with two seed leaves sticking out of the soil.

MORE ABOUT VEGETABLE GARDENING

Looking for some gifts for a gardener in your life or for yourself? Check out my Gardener’s Gift Guide. (This post contains amazon affiliate links that earn me a small commission, at no cost to you. I only recommend products that I use and love. Learn more about my affiliate policy here.

Green pepper leaves.

This post was originally published on March 24th, 2013. On January 26th, 2021 I updated this post with new photos and text.

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4 Comments

  1. Recently, I got a chance to travel with Mike Bacher, the best landscaper in Johannesburg, and we talked about simple ways of beautifying the garden area by installing decorative pots, pebbles, and paver stones.

    1. Thanks. Garden is doing well, but with all the rain and mud everywhere I have to admit our stones are dirtier than ever! Maybe over the weekend I'll clean them a bit. Thanks for stopping by.

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