What You Need to Know About How to Start Seedlings Indoors

Young woman enjoys time seed-starting plants in the winter and early spring

If you’re tired of gray winter months, you may want to fast track spring by learning how to start seedlings indoors. Devoted gardeners have spent that last month pouring over their favorite catalogs, anxious to get on with it.

Wait no more! With the right tools, you can get a jump on spring by starting flower seeds indoors, so you’ll have lush and colorful borders and beds before your neighbors!

Do you prefer growing food for your table? Starting vegetable seeds indoors means you’ll get a bountiful harvest early. Don’t wait for the last frost date to plant your seeds – start your veggies indoors six to eight weeks prior to extend your growing season.

How to Grow Plants from Seeds Step by Step

Starting plants with seeds can save a lot of money when planning your garden. You could go out and drop a fortune at a nursery to fill your flower beds, why should you?

You can also get a better variety of flowers and vegetables. Using seeds means you can purchase them from anywhere in the world instead of limiting yourself to what local growers are producing.

Growing plants from seed is easy:

  1. Choose your seeds
  2. Get cell trays for your seedlings
  3. Add starter medium or potting soil to your trays
  4. Insert 1-3 seeds into each cell
  5. Cover with a fine layer of starter medium
  6. Place trays into a pan of lukewarm water for 15 to 20 minutes
  7. Drain water from bottom tray
  8. Place cells and tray under a grow light or on a sunny windowsill

Seed Starting Mix vs. Potting Soil

You may be wondering if you can you start seeds in potting soil. You can if you use a light-textured mix that contains plenty of perlite, vermiculite, or coconut coir. You can also add these to potting soil to make your own seed starter mix.

When to Start Seedlings Indoors

If you’re wondering when you should start seedlings indoors, make sure you look at the instructions on your seeds. Most recommend starting them six to eight weeks before the last frost date. Some, however, may require longer.

Seedlings growing indoors under LED grow lights

Do You Need a Grow Light to Start Seeds Indoors?

Although you can start seedlings on a sunny windowsill, you’ll need a grow light for more than a handful of plants. Seedlings need a bare minimum of six hours of sunlight, and most windows don’t provide enough.

Luckily, grow lights are inexpensive and effective for starting seedlings indoors. Brite Labs LED grow lights offer the right color spectrum of light for young seedlings, without using excess electricity.

How Far Should Seedlings Be from the Grow Light?

With LED grow lights, you can place your lamp as close as 20 inches from the plant because they don’t put off as much heat as other grow lights.

How Long to Wait for Seeds to Germinate

You may be wondering how long it will take to start seedlings indoors and see your new plants growing. Different plants have different germination times. Some appear as soon as three days after planting, while others could take up to a month or more.

Your seed packets often provide a germination time.

How to Germinate Seeds Quickly

Most plants germinate quickly when the soil is warm. You can speed up their usual germination time by supplying a heat mat beneath your seed trays.

Soaking seeds in warm water overnight can sometimes hasten the process, especially if the seeds have a hard, outer shell, like beans, beets, morning glories, and moonflowers. 

You can also give them a boost by germinating them on a damp paper towel in a closed container before planting them in starter cells.

young flower-seedling carnations are grown indoors

How Do You Care for Seedlings?

Once your seedlings germinate, you’ll want to take excellent care of them until they grow big and hardy enough to plant outdoors.

How Do You Water Seedlings?

Because they haven’t developed a strong root system yet, you should water your seedlings from the bottom. This keeps them from being dislodged, which can happen when you water from the top.

How Often Should I Water Seedlings?

Don’t overwater your seedlings. They should only be slightly moist, and too much water can cause something called “damping off,” which will kill them. Most need to be lightly watered every day to stay viable, but for extra assurance we recommend using a moisture meter.

Transplanting Your Seeds

Soon, you’ll have healthy young seedlings ready to plant in your garden. Don’t be in a rush, though! Make sure that your young plants can handle your current temperatures and precipitation. Young seedlings are especially susceptible to damage from cold and heavy rainfall.

Hardening off is the process of accustoming your seedlings to outdoor life. This means placing them in a protected area while they get used to the temperatures and sunlight outdoors. You’ll move them gradually into the garden over the first week or two before planting them.

baby plants kept in greenhouse for their healthy growth

Filling in Your Borders for Spring

Once temperatures are steadily warm, and all risk of frost is gone, you can plant your seedling in their permanent homes. They should have at least one full and healthy set of their permanent leaves and hardened off before planting.

It’s easy to start seedlings indoors, and it’s a fantastic way to get your landscape and vegetable garden looking lush on the first warm day of the season.

Make sure you use containers large enough to give them room enough to grow. Also, use a light potting mix to provide them with the nutrients they need. Finally, make sure they get the light they need with full coverage from LED grow lights.