Homemade seed starting soil mixes are an easy way to get your garden going fast. Starting your own garden transplants from seed is smart because it gets you a big-time boost in harvesting vegetables from 
the garden; plus, you can grow and try whatever variety you want rather than depending on varieties that the garden center might have. But, if you’re using prepackaged bags of seed starting mix from the store, it can get expensive.
The good news is, it’s easy to make your own homemade seed starting soil mixes with just a few ingredients from the garden center. We’ve been using both recipes below for making “soil blocks” to germinate seeds and grow transplants (see Use Soil Blocks for Super Healthy Seedlings), and find that these recipes germinate seeds as well or better than the mixes we used to get from the store.
Although we use both recipes for soil blocks (the first for 2″ and larger soil blocks and the second for 3/4″ soil blocks), the first recipe also works well for starting transplants in containers. Both recipes are from The New Organic Grower by Elliot Coleman.
- 3 buckets (10 quart bucket) brown peat
- 1/2 cup lime
- 2 buckets coarse sand
- 1 cup blood meal
- 1 cup colloidal phosphate (22%)
- 1 cup greensand
- 1 bucket soil
- 2 buckets compost
To make the seed starting mix, measure the peat into a large mixing container, add the lime and mix. Then add the sand, blood meal, phosphate, and greensand – mix again. Add the soil and compost, mix again. It’s a good idea to start out with good quality peat that doesn’t have large pieces in it, otherwise the mix needs to be screened (I found this out the hard way). The recipe makes about 2 bushels of mix and can be used for “soil blocks” or starting seedlings in containers.
For the very smallest “soil blocks” (3/4″ soil blocks) a different recipe is used that isn’t as rich.
- 4 gallons peat
- 1 cup colloidal phosphate
- 1 cup greensand
- 1 gallon compost
- Mix all ingredients together similar to the recipe above.
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