Tomato Seed Starting Basics

These are the basic supplies you will need for tomato seed starting:

--Clean, small, approximately 1-inch containers, or a tray of cells, with drainage holes in the bottom--you will have one tomato plant per cell or container so make sure you have enough to accomodate the number of plants you wish to grow. These can be created from recycled materials. Just make sure everything has been cleaned thoroughly in a weak-bleach solution before planting or you might transfer some unknown germs to your seedlings.

--Trays to hold the plant containers and water. I think it works better to add water to the tray allowing the plants to absorb the water from the holes in the bottom of the individual container or cell rather than watering the plants from the top of the soil.

--Clear lids that fit tightly over the plant containers to hold in humidity. These are usually part of a seed starting kit or you can use saran wrap.

--Soiless starter mix. This is a sterile type of potting soil designed for seed starting. Using a special mix helps prevent vulnerable seedlings from becoming infected with something in the soil. There are recipes for making your own mix, but I don't have that kind of time or energy! I have tried several brands and my favorite is Natural Beginnings from Gardens Alive!

--Waterproof plant markers and a permanent marking pen, if you are growing more than one type of tomato. I make my own markers by cutting a vinyl file folder into strips with points on one end.

--Water source and a filled water spray bottle

--Small shovel or spoon for stirring and scooping the seed starting mix.

Here are some additional items that may not be essential, but that I include in my seed starting supplies:

--Seeds and containers/trays for companion plants My favorite companions are marigolds and basil and I like to start about 24 basil plants at the same time as I start my tomatoes.

--Accelerated Propagation System (APS) from Gardener's Supply Company. The APS is a kit that contains the cell tray, water tray, and clear dome plus it uses a wicking system that makes it easier for me to keep my seedlings consistently watered and is washable and re-usable year after year.

--A source of bottom heat. This helps seeds germinate faster. The first year I started tomato seeds, I placed everything on an aluminum cookie sheet and rigged up a light bulb underneath for heat. Now, I use Seedling Heat Mats. You may be able to find these locally at your garden store or you can order them online from

On, you'll also find several helpful reviews on this product. Personally I love using these, my seeds germinate in 24-48 hours.

Here are the basic steps to starting tomatoes:

1: Label the appropriate number of plant markers for each type of tomato seeds you will grow and plug in bottom heat source, if you have one.

2: Moisten seedstarting mix--add water to mix in the bag or a bucket, being careful not to inhale any of the dust from the dry mix (it's a good idea to protect your lungs by wearing a face mask for this part). Stir with shovel or spoon. Final mixture should pack into a ball when you squeeze a handful, but not be wet enough to ring out any water when you squeeze it.

3: Scoop moistened seed starting mix into containers, packing it down firmly with your fingers but not tight. Fill container to within 1/4" of the top and place labeled markers in the edge of each container (or cell).

4: Place two seeds of the tomato variety that corresponds to the label for that container on top of the soil mix. [Starting two seeds per cell, should give you at least one good plant per container.] Cover the seeds with about a teaspoon of moistened seed starting mix and firm lightly with fingers. Lightly mist planted seed tray.

5: Place plant containers or cell trays into a water-tight tray with the clear dome fitted on top. Place entire unit on top of heat source (if desired) in a place where it will not be disturbed but where you will remember to check on it daily.

Here's a set-up tip if you are using the APS seed starting kit from Gardener's Supply with a bottom heat source:

Due to the height of the seeds when the wicking system is in place, there is no benefit to using a heat source. So, instead place the styrofoam seed cell tray directly into the water tray (without the wicking system) and place the tray on top of the heat source. You can install the wicking system after the seeds have sprouted and no longer need the bottom heat.

After an hour or so, you will notice condensation forming in the dome indicating plenty of moisture. You won't need to add any water until after the seeds have sprouted.

Your seeds are planted! Remember to open the dome and peek in once a day--that lets in a bit of oxygen and allows you to check for sprouts.

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