CVG substrate

November 20, 2025

CVG stands for coco coir / vermiculite / gypsum.

This is for fruiting mushroom spawn in bins.

Ingredient	snall batch	medium batch	Double
Gypsum	1 cup	1.5 cups	2 cups
Vermiculite	4 cups	6 cups	8 cups
Coco coir	650g	975g	1.300 kg
Water	4 quart	6 wuarts	8 quarts

Gypsum can be sourced from garden store (comes in pellets) or if you have any scraps of drywall laying around the white stuff between the paper layers can also be used.

Vermiculite comes in various sizes, medium is best. Its role is to absorb and hold water.

Coco coir comes in bricks that are 600-650g apiece or in larger bricks. Amounts aren’t exact, 50g one way or other isn’t going to matter. Be careful not to get the kind that has anti fungals in it (common in garden stores). Pet store (for reptiles) is a good source. Coir breaks up easier when it’s moist. Wear rubber gloves to minimize it sticking to your hands.

Mix in a 5 gallon bucket or other container. Small batch yields about half a 5 gallon bucket. Double batch almost fills one.

Mix to “field” moisture. When you squeeze it in your hand some water should come out but not too much.

Put in oven roasting bag on cookie sheet

Place for 30 minutes at 400 degrees F to get the center warm, then turn down to 200 degrees F for another two hours.

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