DIY Seedling Mix: Yay or Nay?

Seed starting has begun on The Farm and I want to share my experience of making my own seed starting mix and comparing it to purchased mixes. For the too lazy to read crowd, my results are as follows:

DIY Seedling Mix: $5.25/cubic foot
Black Gold Natural & Organic Potting Soil: $6/cubic foot
Black Gold Seedling Mix: $16/cubic foot

I went through about 20 cubic feet of commercial potting soil last year just for indoor seed starting – at least 13 of the big 1.5 cubic foot bags. I almost always bought Black Gold Natural & Organic Potting Soil and added more perlite to it for moisture retention. While this isn’t marketed as an actual seedling mix, I’ve had great results with it and it’s far cheaper than the seedling mix. Alas, as a fledgling farmer I’m always after ways to save money on necessities, so this year I wanted to try making my own mix.

After a bit of extensive internet research I focused on the seedling mix recipe provided in this very well-written article from NW Edible.

I was particularly interested in seeing how my figures played out: The author of the article figured her DIY mix cost $70 for a 12 cubic foot batch, with the commercial equivalent costing $597. That’s some major savings!

Here’s the ingredient list along with their current costs here in North Idaho:

One 3.8 cubic feet bale of peat moss, $15
4 cubic feet of compost, $11
2 cubic feet perlite, $11*
2 cubic feet vermiculite, $22*
2 cups of lime, $1*
3 cups fertilizer, $3

(*Note that I had to buy larger bags of the lime, perlite, and vermiculite, but I adjusted the cost for the breakdown of this mix.)

This adds up to $63 for a 12 cf batch of premium seedling mix, or $5.25 per cubic foot. I got excited about the consistency of this blend after mixing it all together, not to mention being able to play in the dirt in the middle of February. If you’re into Dirt Therapy, then you know what I’m talking about. I actually only made a quarter batch of the above recipe and it filled two 18-gallon Rubbermaid totes.

I liked knowing exactly what’s going into the mix and in which quantities. I wish I could have used my own compost, but my pile is currently frozen so I bought a bagged commercial brand made in Montana. All of these components were readily available to purchase locally in my area which is why I went with this recipe.


As a side note, I’m aware of the ecological debate about using Canadian peat moss because it’s not a sustainable resource. As is the case with everything, one has to weigh the options and just try to do what’s best overall. One option being coconut coir, which I have used in the past and think it’s an awesome product, but it’s not here. I haven’t found a local supplier and to have it shipped just to me is not only ridiculous, but would end up costing about twice as much as the peat.

In comparison, the Black Gold Potting Soil costs $9 for a 1.5 cubic foot bag, or $6 per cubic foot. I guess I got lucky finding a nearby store (Country Co-Op) who sells this for $9, because the exact same bag runs a whopping $28.49 on! Even the smaller 16 qt bag (about half a cubic foot) costs $13.82 at that store that begins with a W, according to their website.

If I went all out and purchased the Black Gold Seedling Mix, it would cost $8 for a 16 qt bag at my local farm store, or $16 per cubic foot. That’s expensive when you consider I may go through 20 cubic feet or more per season.

Clearly, DIY wins but I’m also going to keep using the Black Gold Potting Soil if my batch runs out and I don’t have time for another mix. As far as comparing plant growth between the two mixes, that may be another article down the road since I’ve only just started with the DIY mix.



One thought on “DIY Seedling Mix: Yay or Nay?

  1. We mix our own rooting media, but it is cheap, and not available otherwise. We also mix our own potting soil, just because it is less expensive that way. Much of it is recycled material that we only invest our time into.
    I am very surprised by the quality of the ‘compost’ that the gardeners I work for (at another site) get just from recycling their greenwaste. They do not put much work into it. It is just easier to compost much of the waste than to dispose of it. When it is done, they can mix it with native sandy soil for a very rich bedding media. They have even used it in large urns like one might use soilless media! I do not think that I would want to use it for potting, but they have no problems with it!


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