Never heard of it before? Now you have! This is my soil mix recipe. Hat tip to “Mr Canuck’s Grow” on YouTube for bringing my attention to it.
70% coconut coir
20% quality worm castings
10% aeration (perlite/vermiculite)
Organic dry fertilizer blends
(The next 2 are optional, but recommended)
1 scoop of home soil (provides trace minerals and good luck)
Mycorrhizae, when transplanting
As you may have guessed from the name, this is my homemade version of the popular bagged potting mixes on the market. It’s preloaded with microbes and organic fertilizers but I wouldn’t quite call it a “living soil” - it’s sort of a shortcut to that.
There are distinct advantages to making it yourself. It can save you some money. Since you’ll be mixing it up fresh, you’ll know exactly what went in it, and when it went in.
Maybe you can even add some of your own inputs if you have a source of good compost or organic fertilizer. Or coconuts. You can sort of treat this recipe as a template.
The coco coir is serving to create the soil structure. It’s nice and fluffy, so it holds plenty of air, but it can also hold many times it’s weight of water. The air is the critical factor though - if you’ve been growing in straight topsoil prepare to be amazed.
You can save some money if you buy it in bales but it needs to be rinsed properly. That’s a topic in its own right and I went into more detail about it here.
The worm castings should need no explanation. Even people who don’t garden know you want worms in your garden. They’re little fertilizer factories and they poop out black gold for your plant.
If you don’t have a source of good quality compost, or even if you do, pure worm castings are like the top of the compost food chain. “Vermicompost” is generally a blend of worm castings and peat - you don’t want that, we’ve already added the peat component.* Look for 100% pure castings, especially if you saved some money going with the brick coco.
*Vermicompost will work fine too, you’ll just want to adjust the ratio - maybe add a little more.
The compost ingredient adds readily available nutrients for your plant, and also inoculates the soil with beneficial microbes. These will work in harmony with your plant to break down the organic fertilizer inputs into the nutrients that your plant needs.
For the aeration ingredient, you can go with trusty old perlite or vermiculite. Or if you’re starting to nerd out on this soil stuff (you’re still reading so I’ll take that as a yes) there are organic options like rice hulls.
For the fertilizer, I’ve been using the Down to Earth blends, 4-4-4 Vegetable Garden for veg, and 4-8-4 Rose and Flower for flower. These are a mix of things like kelp, fish bone meal, seabird guano, feather meal and so forth. These ingredients won’t all be readily available as nutes for your plant; the microbes in the soil will break them down over time, creating sort of a slow release.
You could add these components separately and create your own fertilizer blend, but make sure to consider the various feeding schedules for each one. I think there are fully veganic options available as well.
Why the home soil? Your plant and it’s soil are a living system we still don’t fully understand. I don’t have any science to back this one up, but there’s something that the plants and soil in your location know about growing there. In my case, my soil is also quite sandy and it’s a good source of silica.
Since we’re sort of taking a shortcut to living soil using this recipe, I like to add in the mycorrhizae. I’ve been aware of that stuff since I got interested in vegetable gardening years ago. I knew it as something you wanted in a good healthy soil, but I didn’t know you could buy it in powdered form until I started growing my own medicine.
It’s expensive, and you do need to select one that’s formulated for cannabis. You might even have enough of it in your compost already, so you may not even need it. But I’ve been using it. I generally apply it at transplant- I’ll sprinkle some directly on the roots and also the soil bed I’ve made in the new pot.
I always mix up just the right amount of my potting soil either on transplant day or a couple of days before. That way I know Day 1 of the feeding schedule for the fertilizer I use. I don’t use any bottles at all with this blend. I just stick to the directions on the box - in my case, feed (or transplant) twice a month.
I just eyeball the amounts. I try to actually calculate the amount of fertilizer that’s directed but I just eyeball that too. The plant won’t mind a little extra love with these nutes, if you’re making it up fresh.