Pasteurized Mushroom Substrate Bag – Coco Coir, Vermiculite & Gypsum, 4.5 lb

Skip the mixing and pasteurizing. Our bulk substrate is a pre-hydrated blend of coco coir, vermiculite and gypsum (CVG) at field capacity, ready to mix with colonized grain spawn.

What's Included

• 4.5 lb bag of pasteurized CVG bulk substrate, the same bag that comes in our kits
• Glove pack (nitrile gloves and alcohol prep pads)
• Instructions and a FunGuy sticker

Grain spawn, tub and culture are sold separately. Add our 1 lb Rye Grain Spawn Bags or get both in the Rye Grain + Substrate Kit.

How It Works

1. Prep: Clean your tub or bin and put on gloves.
2. Spawn: Break up fully colonized grain spawn and mix it evenly with the substrate. Use 2 lb of grain spawn (two 1 lb bags) per substrate bag, the same ratio as in our kits.
3. Colonize: Level the surface, cover, and keep dark at 75–80°F until it's covered in white mycelium.
4. Fruit: Crack the lid for fresh air, add indirect light, and mist only when the surface looks dry.
5. Harvest: Pick before the caps flatten, rehydrate, and repeat.

Timeline

• First harvest: about 3–5 weeks after inoculating your grain, depending on species and conditions
• Up to 3 flushes

Ideal Conditions

• Colonization: 75–80°F, in the dark
• Fruiting: 65–75°F, indirect light, fresh air, high humidity
• Container: a 16 qt tub (the size in our Monotub Starter Kit) or similar

Yield Expectations

Yield varies with species, culture and conditions. With 2 lb of spawn, expect up to 3 flushes; rehydrate between flushes.

FAQ

What is CVG? Coco coir, vermiculite and gypsum: a clean, moisture-holding bulk substrate that's easy for beginners.

Which mushrooms grow well on it? Works with a wide range of mushroom species. Lion's mane and shiitake prefer hardwood sawdust, so CVG isn't ideal for them.

Is it pasteurized? Yes. The substrate is pasteurized, the standard treatment for a bulk substrate that you mix with colonized grain spawn.

How long does it keep? Unopened, it lasts 2–3 months, but use it as soon as possible so it doesn't dry out.

Do I need to add water? No. It's pre-hydrated to field capacity.

100% Success Coverage

Every FunGuy kit is made in our Rhode Island lab and backed by our 100% Success Coverage for 30 days. If your kit arrives contaminated, send us a photo and we'll replace it free of charge.

More help: Growing Guides.