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How to Germinate Seeds Indoors

Learn how to germinate seeds indoors in this easy, step-by-step tutorial. With a few tips and tricks, you’ll be growing vegetables and flowers in no time.

Basil begins to grow inside cells of a seedling tray in an effort to learn how to harden off seedlings. (And after learning how to germinate seeds indoors.)

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Here in the midwest, we’ve been getting lots of spring weather already. I am more than happy to be getting an early spring this year, and one way I’m preparing my garden is through seed starting my vegetables and flowers indoors. 

Starting seeds indoors first gives a gardener the chance to get a head start. Instead of waiting to directly sow seeds in the ground around May, you’ll be transplanting pre-started plants at this time. 

This means a longer growing season and a higher yield of crops.

I don’t know about you, but if I’m going to put in all the work to grow crops, I want to be able to reap as many rewards as possible. Higher yields allow you to give extras to friends and family or stock up after preserving them.

I know it’s only early March, but I am thrilled to be getting my hands in the dirt and to see some color popping up on our tabletop from sprouting young seedlings. It may not look like much to some folks, but it’s honest work.

You can even recruit children to help you in these preparations and give them a mini science lesson as you work. 

Now let’s get into all the supplies you’ll need and your steps to starting seeds indoors. Don’t worry, I also have a few tips to share to ensure your seeds germinate this growing season. Learning how to germinate seeds indoors doesn’t need to be intimidating.

A tray of started seeds is shown with the words "how to start seeds indoors"

How to Germinate Seeds Indoors

What is germination?

This simply means that a seed will sprout, eventually growing into a plant. Germination requires water, sunlight, and healthy soil for success. 

Benefits to starting seeds indoors

  • Start gardening sooner
  • Longer harvesting season
  • Prevents wildlife from messing with seeds or delicate young seedlings
  • Better germination rates since you can better control temperature, light, and moisture
  • More affordable than purchasing pre-started plants to transplant
  • Most crops will thrive if started inside first

When to start seeds indoors 

Generally speaking, 6-8 weeks before your frost date (which varies by region) is the best time to start seeds indoors. This gives them enough time to germinate, start developing into strong seedlings, and develop sturdy root systems that will ensure their survival during transplantation later on. 

Almanac.com is a great resource where you can insert your zipcode to find not only your growing zone but also a chart with indoor seed starting dates. I highly recommend using this. Eventually you will get in a routine and remember the time to start them, but it’s great for beginners or those managing extra large gardens with a wide variety of crops.

Seeds are germinated indoors and a plant label is used to label the type of plant.

How to Germinate Seeds Indoors

Materials and Tools | How to Germinate Seeds Indoors

Seed starting soil

Seeds of choice

Seed starting trays, cells with drainage holes, and covers (I used these HERE and love them)

Hand shovel

Dibber, optional but recommended

Watering can and spray bottle

Plant labels

Table, bench, or open shelves

Heat mat, optional

Grow lights, optional

Steps | How to Germinate Seeds Indoors

Add soil to cell trays | How to Germinate Seeds Indoors

Using a small hand shovel, scoop the seed starting soil into the cells. Fill them to the top. Then use the shovel to smooth them out and level them off. I also scrape any soil off the edges to keep them nice and tidy.

How to germinate seeds indoors is shown by filling cells with soil.

Use a dibber to create holes for seeds | How to Germinate Seeds Indoors

I love using a dibber to make a little hole for the seeds. A good dibber usually has measurements along the shaft to indicate depths. This way you can be sure you’re planting the seeds deep enough (but not too deep that light won’t reach them).

A dibber is used to create tiny holes in the cells of trays.

Add two seeds per cell & cover loosely | How to Germinate Seeds Indoors

Be sure to read your seed packets to plant the seeds at the right depth and for any other special instructions. Add two seeds per cell in order to increase your odds of success. If one fails, you will more than likely have the other sprout. This almost nevers happens to me, but it’s a nice insurance policy just in case. 

Next, cover it loosely with soil. You can use the dibber for this also. 

Seeds are added into small pits of soil.

Water until soil is moist and move to a warm, well lit area | How to Germinate Seeds Indoors

Using a watering can or a sprayer to pour water over the cells in the trays. Do this just until the soil is moist. Even if you overwater, your drainage holes will allow any extra to drain out. The tray below will catch any extra water. 

Then cover the trays with their covers and place them in a well lit area of your home. Using a plastic dome cover to shield the seeds ensures the environment is both warm and moist enough for germination. Don’t skip this step. You can find a spot near a window, preferably facing the east or south, or use grow lights that you can program to give direct light for a set amount of hours per day. 

Be sure to keep the soil and seeds moist, watering at least once per day until they germinate. After germination, you still need to keep them moist until well established–but you should be able to back off on watering just a bit. Later you will transplant them after the last frost date.

A plant label is added to a tray of seeds in order to show a step for how to germinate seeds indoors.
Trays are placed in a window in order to get sunlight.

Tips for Success | How to Germinate Seeds Indoors

I prefer to use a watering can to water the seeds before they germinate. A spray bottle can be used, but a watering can disperses much more water and ensures water is actually getting to the seeds and not just hitting the surface. It is much faster to use a watering can, too. However, once they’ve sprouted I recommend using a spray bottle to keep them damp and prevent them from being overwatered.

Once the seedlings have sprouted, try sprinkling ground cinnamon around them in the soil. Cinnamon helps combat and prevent fungus growth, which is a common occurence for some plant varieties. This will help your plants stay healthy.

If more than one seed has sprouted per cell, simply pluck the extra one and discard. This may seem like a waste but it’s not. Seeds are very inexpensive and adding one extra ensures at least one of them will sprout so you don’t waste time and space on nothing. The extra one needs to be thinned out from the cell, so they aren’t crowded and competing for nutrients. 

When seedlings have a healthy amount of growth (several inches tall), you can lightly brush your hands across the tops of them on a daily basis. This mimics the strength of wind and helps them get used to conditions they will experience once transplanted outside. You can also use an oscillating fan if you have one to program on for a gentle breeze each day.

Marigold seedlings begin to sprout from their container pots.

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