Coco coir soil mix for cannabis.

Coco coir soil mix for cannabis.
Peat moss can also be substituted for coco coir.

Assemble the items needed.

Container for plant, size you’re going to use.
Tarp or big bin for mixing soil. A big bin is best, mix needs to sit for a while.
1-2 cup pet food scoop.
1 quart plant sprayer
Face mask … perlite is very dusty.
Expanded coco coir
Perlite
Vermiculite
Worm Castings
Bone meal
Blood meal
Epsom Salts
Fat free powdered milk
Comfrey
Mycorrhizae

Never pack down anything…This mixture is done by proportions to the container, can be scaled up or down according to need. Use your container for measuring. This is for a full bag, there will be some leftover, store in a lightly covered container in a dark cool spot. Remember though the mix will compact slightly when watered.


Fill grow bag with coco coir to the top. Empty onto/ into tarp or bin. Fill grow bag half full with perlite, pour on top of coir, mix. This is an eyeball measure with perlite err on the generous side. We’re after super drainage.

Fill grow bag one quarter full with vermiculite use scoop notice approximately how many cups you’re putting in. Repeat with Worm Castings, with a value of N 1, try to stay as close to proportion this is for moisture retention and the start of fertilization. Pour onto coco mixture and mix again thoroughly.

Using the scoop add 1-2 cups of chopped dried comfrey. This is the main fertilizer. Russian Comfrey has a NPK value of N 1.80/ P 0.05/K 7.09.

Mix again thoroughly.

Using the scoop add 1/ 2 cup Bone Meal, light 1/2 cup blood meal almost a quarter cup. Bone meal adds calcium for root development. Blood meal is another nitrogen boost. This ingredient can be skipped if you want. Too much nitrogen isn’t good for seedlings. You can add later as a side dressing if needed.

Using scoop add 1/4 cup Epsom salts. Coco coir is very deficient in cal/mag, hopefully some was added during the coir expansion soak. If not sidedress as needed.

Add Mycorrhizae according to package directions. Sprinkle on approximately 4 oz. Powdered milk This is giving the calcium a jumpstart it will be absorbed quickly…the bone meal takes a little time to breakdown.
It’s also food for the mycorrhizae

Mix very thoroughly as you’re mixing, spray down mixture to start to wet, this will activate the ingredients. Mix and wet, again and again till you can make a clump of damp soil in your fist and it doesn’t crumble or drip any water.

Let this mixture sit lightly covered with towels for a couple weeks allowing the ingredients to get to know each other. One week before use fill grow bag, place in saucer and water till water runs out. Stop. Let sit, then stir lightly every day to distribute moisture evenly.

Test porosity…I like my 3 gallon bags to hold a solid half gallon of water…I can pour that amount of water in and get no draining…but if I bump that up to 3/4 gallon runoff starts. I know now, how much water the bag hold without roots. Watering amounts will be variable as growth occurs…but a baseline has been established.

This is the start of your living soil mix, it should be used over again, it only needs to be fortified between uses. Here’s how.

After harvest remove the main plant stem. I usually empty the bag into a big bin to work in. Break up a remove big chunks of the roots saving the soil. Don’t worry about getting all the roots out it’s a good mix into the soil they act like coco coir. I screen my soil through 1/4 inch hardware cloth. It breaks up the soil chunks and mixes the root stuff nicely. When that looks like I can run my fingers through it freely I start to add the boosters to the soil.

Adding boosters to the soil is super simple. It’s simply adding small amounts of everything on the list from Worm castings down the rest of the list. I usually throw in a little more perlite also … just because I love a really porous growing medium.