How to Start Seeds | Seedlings in a Seed Tray

Do you know how to start seeds for your garden? Seed starting doesn’t have to be complicated. Follow this how-to guide to get started!

Is it really necessary to start seeds indoors? Well, no… you can grow food without starting seeds, BUT  if you are looking to grow an efficient, sustainable, and highly productive garden, then seed starting is very important. 

Here’s why:

  • Starting seeds indoors can give your garden a head start on the growing season. In doing this, you are able to start growing 6-8 weeks earlier than you would if you were direct sowing.
  • When you start your own seeds, you are taking more control over your garden. You are able to decide what happens to the food that you grow from the very beginning. This is much more sustainable than purchasing transplants from the garden center each year. 
  • Seed starting saves your money because seeds are much less expensive than starts purchased from the store. You can also save seeds to plant next season if you plant heirloom seeds. This saves even more money.
  • Starting your own seeds can add variety to your garden. There are many varieties of seeds available that you cannot find in transplants at your local grocery store or garden center. Buying and starting seeds allows you to broaden the types of plants that you grow.

How to Start Seeds for the Homestead Garden

When Should You Start Garden Seeds?

Determining when to plant your garden seeds doesn’t have to be complicated. Find out your gardening zone to determine your growing season. Then find the expected last frost date in your area. Work backward from this date using the information from your seed packets. 

For example, I live in zone 7a. The growing season here usually lasts 8-9 months. My last expected frost date is April 10. If I have a seed packet that says to start indoors 6 weeks before sowing outdoors (or before the last frost), I would start those seeds around the end of February.

Seed Starting Supplies

When it comes to seed starting supplies, you can go as simple or as fancy as you like. Just make sure that you at least have containers with good drainage, a seed starting mix, a light source, and something to water with.

1. Seed Starting Containers

There are several options for seed starting containers. 

Seed trays 

A traditional seed tray with a bottom tray and a humidity dome allows for bottom watering and the dome creates a greenhouse effect for quick germination. 

Newspaper Pots

The DIY seed starting pots are cost-effective and biodegradable. 

Peat Pots

Peat pots allow you to skip the plastic containers, but they can cause the roots to become compact and stunt the growth of the plant. It is best to break up the pot a bit when transplanting.

Egg Cartons

Reuse cardboard egg cartons for seed starting. 

Egg cartons used for seed starting

Soil Blocking

Soil blocking is the process of creating compact blocks of soil to start seeds in without a container. This method allows you to avoid transplant shock and reduce your plastic use. 

**If you use a container without a humidity dome, add plastic wrap over the top until the seeds germinate. Remove the plastic once seeds have sprouted.

**Add drainage holes to the bottom of any container that doesn’t already have them.

2. Seed-Starting Mix

When starting seeds, it is important to use a quality growing medium. Don’t use your garden soil because you could inadvertently transfer diseases to your seedlings. 

Seed-Starting mix and potting soil are very different. Potting soil typically contains compost and/or field soil so it can contain bacteria and fungi that you don’t want to introduce to your seeds. Potting soil is also more dense and heavy than a starting mix so it can weigh down seeds that are trying to germinate.

Seed-Starting mixes usually don’t contain any soil at all. They are considered sterile in the package because of this. Starting mixes are also much lighter than potting soil so it is better suited for germinating seeds.

3. Light Source

Seeds and seedlings need 12-16 hours of light each day. You will need a light source directly above the seeds to achieve this. 

There are a couple of options for seedling light sources:

Grow Light

LED Grow lights made specifically for seedlings typically use blue and red lighting, but some are now made to emit full-spectrum white light. 

Seeds under LED grow lights

Fluorescent Lights

Fluorescent t5 lights are commonly used for seed starting. This is a more affordable option than LED grow lights and they work very well. You can purchase a large shop light and hang it over your seed trays.

4. Spray Bottle or Watering Can

A spray bottle is important to use before the seeds have sprouted. Use it to gently mist the soil as needed.

After the seeds sprout, use a watering can to bottom water your seedlings.

5. Heat Mats

Heat mats or germination mats help to speed up the germination of healthy seedlings by keeping the seed starting mix consistently warm. They aren’t needed after the seeds sprout. 

6. Fertilizer

A good fertilizer is added to the starting mix after seedlings develop their true leaves. This is because seed starting mixes don’t have many nutrients so they need to be added in. Use a quality fertilizer from your local farm store or worm castings. 

Transplanting seedlings into the garden

Steps for Starting Seeds Indoors

STEP 1: Gather Supplies and Set Up

Go through the supply list and gather what you need for your seed starting setup. Prepare the seed starting area with these supplies and get ready to sow.

STEP 2: Add Starting Mix

Add the seed starting mix to a large container and pre-wet it. Sprinkle in water and mix until it is damp. This is an important step so don’t skip it. If you don’t pre-wet your seed mix, it may repel water off the top keeping it from your seeds. 

STEP 3: Sow Seeds

Place 2-3 seeds in each seed cell at the depth recommended on the seed packet. Gently press down the starting mix on top of the seeds. 

Add the humidity dome or plastic wrap on top. Remove the dome or plastic wrap after seeds have sprouted. It is recommended to have the seed trays on a heat mat until the seeds germinate.

STEP 4: Water

Check the starting mix each day for moisture. If it is moist, there is no need to water. If it is drying out, mist the top of the soil before the seeds sprout. After sprouting, you can begin to bottom water instead of misting on top. 

STEP 5: Move Under Lights

When the seeds have sprouted, it is time to remove the heat mat and the humidity dome. At this point, the seedlings need to go underneath lights. Keep the lights just a few inches above the seedlings to avoid them becoming leggy.

Seedling emerging from seed starting mix

STEP 6: Fertilize the Seedlings

Most seed starting mixes are low in nutrients because the seeds get what they need from the seed casing as they germinate. After they have sprouted and formed true leaves, they need additional nutrients to thrive. Add a quality fertilizer to keep them healthy and strong.

STEP 7: Thin Out

Choose the strongest seedling in each cell to continue growing. Remove the rest by snipping at the soil level. Having multiple seeds per cell will cause your seedlings to be stunted as they are forced to share nutrients. 

STEP 8: Re-pot

Seeds that were started in small cells need to be potted up into larger containers when they reach about 3” and have true leaves. This will allow the roots to grow bigger and stronger than they would in a small cell.

Seedlings being repotted into larger pots

STEP 9: Harden Off

1-2 weeks before transplanting you should begin to harden off your seedlings. As long as the daytime temperature is above 32 degrees F you can bring your seedlings outside each day. Start off by putting them outside for one hour during the day and add an hour of sun each day after that. 

STEP 10: Transplant

When your seedlings are hardened off, they are ready to be transplanted. Prepare the garden area and dig holes just a little larger than your plants. Transfer the seedlings into the holes keeping as much of the starting mix around the roots as possible. Refill the hole with soil and gently tamp down. Keep the seedlings watered well and watch out for signs of transplant shock.

How to Start Seeds Indoors