For those who are serious enough about organic (or sustainable) growing with soil, I'd like to pass along an organic seeding soil mix which has germinated over 95% of my seeds. This will completely cut down your cost compared to any seeding soil mixture you'll find online. And, by the way, chances are you won't find any local store carrying organic seeding soil. However, you'll find all of these components are your local greenhouses, nurseries, farmer's market, etc. As a companion with your seeding/propagation, it is necessary to purchase a soil block maker, such as this one. A 2" x 2" soil block is more than adequate for any strain, and the preset depth of the seeding hole is perfect for this size seed

Seedling mix for soil blocks or seedling flats

Sphagnum peat moss: 2 3-gal. buckets
Lime: ¼ c.
Greensand: 2 cups
Blood meal: 2 cups
Bone meal: ½ cup
Vermiculite: 1½ buckets
Compost: 1½ buckets


Directions for mixing

• Add peat to cement mixer or mixing barrel.
• Spread the lime and fertility mix over the peat.
• Mix these ingredients thoroughly.
• Add the compost and vermiculite and mix well again. When done, examine the distribution of vermiculite to ensure that it has been mixed in evenly.

Note that all bulk ingredients should be screened through 1/4 -inch hardware cloth. Well matured, manure-based compost should be used (avoid poultry manure and wood-chip bedding).

The whole recipe can be found at the ATTRA website. I think you'll find other ingredients simply are not necessary and may actually cause more harm than good (e.g. nute burn). For mixing the ingredients, I find cement mixers a bit too expensive (either to rent or own). I mix large quantities in a horse-watering troft and a shovel. Just make sure in all your mixing it is thorough and as evenly spread as possible.

Once I find a suitable organic potting soil mixture (the one I'm using now is nute burning the plants--I need to make adjustments in the mixture), I'll post that as well. The potting soils located at ATTRA simply have too many nutes that cause burn. I am fairly certain it is the collodial phosphate rock that is damaging to the organic potting soil, but that is just a guess. The organic potting mix I created is this:

Organic potting mix

1 part sphagnum peat
1 part peat humus & manure mixture (short fiber)
1 part cotton burr compost
1 part vermiculite


to every 80 qts. of this add:



1 cup greensand
1 cup colloidal phosphate
1½ to 2 cups crabmeal, or blood meal
½ c. lime

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