Potting Soil Mixes for Bulk and Small-Scale Garden Use
Place of Learning: 

ESY Berkeley Teaching Staff
Edible Schoolyard Project
Berkeley, CA

This resource provides three soil mix recipes. Each of these mixes is a healthy and effective combination of ingredients, whether you are working on a larger plot of land or seedling trays.
Seedling Tray Mix
  • 2 5-gallon buckets of sphagnum peat moss, run through a sifter first and moistened (you may also use coco-peat moss which is a renewable resource material that we use in our ESY potting mixes; see reverse for more information)
  • 1 1⁄2 buckets vermiculite (OMRI certified)
  • 1⁄2 bucket worm castings
  • 1⁄4 bucket perlite (OMRI certified)
  • 1⁄4 #10 can bone meal
  • 1⁄4 can kelp meal
  • 1⁄4 can gypsum
  • Makes enough for 20 125-200 cell trays


Mix together well in a wheelbarrow, making sure that your ingredients are moist. Fill your seedling trays, making sure that your mix is settled in the trays. Be sure to reserve some mix and vermiculite for covering the seeded cell-flat trays once they are sown.

Seed Flat “Breakfast Mix”

For starting seedlings in open boxes / no compost required.

Fill a wheelbarrow 1⁄2 full with organically certified potting soil (OMRI certified – Black Gold is a good commercial mix). Add some garden soil to the mix as a local “innoculant.”

Mix in:

  • 1 5-gallon bucket peat moss
  • 1⁄2 bucket vermiculite
  • 1⁄2 bucket perlite
  • 1⁄2 bucket worm castings
  • 1⁄4 #10 can kelp meal and gypsum
"Lunch Mix"

For growing-on seedlings or vegetatively propagated cuttings and divisons. In a wheelbarrow, mix:

  • 1/3 potting soil (OMRI certified) plus farm soil
  • 1/3 sifted compost
  • 1/3 peat, vermiculite, perlite, worm castings combination 1⁄4 #10 can kelp, bone meal & gypsum