How to Make Homemade Soilless Seed Starting Mix

For those of us who start seeds indoors, purchasing bags of soil mix can get expensive and the ingredients can contain unknown pathogens. I start a lot of seeds indoors and was sick of spending money on store bought soil. During the gardening off season, I did some research and experimenting on how to make a quality seed soil starter at home.

I had no idea making my own soil mixture would be this simple. I use 4 ingredients that are easy to source and don’t cost a lot of cash. The worm castings are an optional addition that will add extra nutrients to the soil without any harm. If you choose to use the worms, keep it between 10-20% of the mixture.

Make sure to find a large tub or bucket to blend all the ingredients together. With the block of coconut coir, you will need to pour a couple quarts of water over the brick to allow it to expand out. After it is fluffed up, I dump in the perlite, vermiculite, and worm castings. It is easiest to use your hands to blend it all together. You are all set to start sowing those seeds! This soil can also be used for winter milk jug greenhouses. Happy Gardening.

Why Use a Special Mix for Starting Seeds

Seedlings are very tender and cannot thrive in regular potting soil. Germinating seeds need air flow, moisture retention, and good drainage. This mix provides all of the above. Note there are no nutrients in the mix if you do not add the worm castings. Plants won’t need a fertilizer though until after they have a couple of sets of true leaves. Which at this time a weak solution of a commercial brand plant food may be applied.

Ingredients

1 Block Coconut Coir or 1 Bag of Sphagnum Peat Moss

2 Cups Perlite

2 Cups Vermiculite

Worm Castings (Optional)

My Favorite Seeds to Start Indoors

Here are the seeds I start each spring indoors with the most success.

Peppers
Tomatoes
Onions
Basil
Snapdragons
Pansies
Broccoli
Coleus
Parsley
Marigolds