Mix Up Your Own Seed Starting Mix

Photo by Gayla Trail

I posted this recipe a year ago but it is buried in a larger post and I decided it would be better-accessed if it had its own place. Making your own mix is SUPER easy and worth the small effort if you are growing a lot of seedlings.

Seed-Starting Mix

These are the ratios I prefer. If you don’t need a huge batch you can use this as a basis for choosing a store-bought seed-starting mix. Always read the label and look for an ingredients list. Most popular brands have chemical fertilizers added that are unnecessary and will defeat the purpose of growing organically.

Instead, buy a basic mix and add in your own organic materials. I suggest adding a touch of vermicompost and watering your plants with a diluted sea-kelp mix. To be clear, seeds do not require any fertilizers until they produce their first set of “true leaves“. In basic terms this means the second set of leaves you will see. The first leaves that appear are called “seed leaves” and feed the seedling until the first “true leaves”appear.

  • 1 part peat or coir (Coir is a sustainable peat substitute made from coconut husks. Peat is mined from marshland, destroying natural habitats. When you can, use coir.)
  • 1 part perlite (popped volcanic ash that creates good drainage.)
  • 1 part vermiculite (water absorbing material made from the mineral mica)
Gayla Trail
Gayla is a writer, photographer, and former graphic designer with a background in the Fine Arts, cultural criticism, and ecology. She is the author, photographer, and designer of best-selling books on gardening, cooking, and preserving.

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10 thoughts on “Mix Up Your Own Seed Starting Mix

  1. I’m never sure I understand the use of ‘parts’ – are you talking equal volumes or equal weights of the components? Are they usually sterile as well? I understand that’s the big advantage over using a soil based seeding mix.

  2. Either really. Any method of measuring is fine as long as the ratio is 1:1:1. So it could be equal cups or equal buckets depending on how much mix you want to make. These ingredients will all be sterile when you purchase them.

  3. I live in Toronto Gayla, pretty close to you i think, and i wondered where i can get these things from? Bear in mind i’ll be getting around by bike or TTC. Last year i tried fiesta farms and i could only find regular seed starting mixtures, is there anywhere else that’s close-ish?

  4. Leila: I’m in the same boat as you (biking to get my supplies) so I know all the local places and what they sell.

    Fiesta Farms was so disappointing in the container soil department last year. Everything had fertilizers and crap in it!! I would try Home Hardware for bags of perlite and vermiculite. Grassroots Environmental Store (Bloor and Bathurst or there is a second location on the Danforth) sometimes carry bricks of coir. I’d suggest calling them to be sure they’re in stock. The bricks look small but are so compressed they expand to be quite a good amount. They also sell organic fertilizers that can be added later on.

    If you are looking for a prefab seed starting mix I would recommend the one made by a company called Nature Mix. They do include peat but it is sustainably harvested. You can buy their stuff at Loblaws. I go to the one at Christie and Dupont. There is a small garden shop at Queen and Gladstone that sells some of their container soils but they do not sell the seed-starting mix. I go there for the large soil bags because I can walk them home in my granny cart.

  5. just made 30 gallons of my potting mix. will be great for the 60 tomato plants I plan to plant this year. so much better than Mirical grow…

  6. Hi all,
    I can’t stand the thought of any gardener spending half a day transporting supplies when they should have their hands in the soil and a smile on their face(s) instead… I have offered my soil-hauling serivces on YGG before and I will keep offering until someone asks for my help… ATTENTION: All Toronto’s West End Community Gardeners! My car is an old, gold Sundance and the roof IS the roofrack… I can load a ton of soil, and bales of peat/coir/mulch on top of, and in, my car. I have a sturdy rockclimbing rope to tie it all down. I’m an artist; I do this ALL the time. Weekends are best. Ask.

  7. Hi, Thanks for the recipe, I will be trying this recipe out very soon, as I am starting my winter veggie garden this weekend (I live in the Southern Hemisphere). I used a similar recipe last spring, but it was 1 part sifted compost, and 1 part vermiculite. I seemed to work fine, I was just wondering what others thought of using compost in the seedraising mix instead of peat or coir, is this a bad idea? Please let me know what you think

  8. Hi! thanks for the Coir input, definatly like the sustainability aspect of that idea. For us down in the drier parts of the world i suggest using some sand in the seed-starting mix along with compost and worm castings. This is especially good for our grasses and forbs!

  9. Hi, I live in Tajikistan where all those things you described are unavailable… so I have used my own mix of old coffee grinds/ tea leaves, clay soil and grass compost… with varying results! Any other ideas for home grown seed soil mix? (Baring in mind there are NO garden supplies here)

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