3 CVG Recipe Options
Coco coir only, coir with vermiculite, or the full CVG recipe with gypsum
CVG Substrate Calculator
Our free CVG calculator is a mushroom substrate calculator that finds the exact amounts of Coco Coir, Vermiculite and Gypsum for your CVG recipe. Enter the substrate volume you need or your spawn amount, pick your spawn to substrate ratio and get instant results for your monotub. No signup required.
Jump to CalculatorSpawn to Substrate Ratio
Choose from 1:1 to 1:5 with a density and colonization speed guide
Metric and US Units
Switch between grams and ounces, mL and quarts instantly
100% Free
No signup, no hidden costs, use it as often as you need
Mushroom Substrate Calculator
L
Coco Coir
Required
Base substrate. Perfect water retention and sterile field capacity.
Vermiculite
✓ Added
Prevents compaction. Better air exchange and moisture retention.
Gypsum
✓ Added
Stabilizes pH. Adds calcium and sulfur. Prevents clumping.
Formula: CVG — 100g Coir : 27g Vermiculite : 17g Gypsum : 600 mL Water
Note: The CVG formula uses boiling water for pasteurization. No pressure sterilization needed. Always wait until substrate is fully cooled before adding spawn.
How to Make CVG Substrate: Easy CVG Recipe
Follow these 8 steps after calculating your amounts with the CVG Calculator above. This CVG recipe uses coco coir, vermiculite and gypsum and works for monotub grows.
1
Boil Your Water ~5 min
Bring the calculated amount of water to a full boil, either in a kettle or on the stove. The boiling water is what pasteurizes your CVG substrate, so make sure it is at a rolling boil before adding it.
2
Mix Coco Coir, Vermiculite and Gypsum with Boiling Water ~10 min
Add all your dry CVG ingredients (coco coir, vermiculite, gypsum) into a large pot or bucket and give them a quick mix. Then pour the boiling water over the mixture and stir well until everything is evenly saturated.
Use a large enough container! Coco coir expands dramatically when hydrated. It can increase up to 8x its dry volume. A coco brick that looks small will fill a large bucket, so always go bigger than you think you need.
This is pasteurization, no sterilization needed. Coco coir is naturally resistant to competing organisms, so boiling water is more than sufficient. You can use coco coir bricks, loose coir or coco powder. All work equally well.
3
Cover and Wait 4 to 6 Hours 4 to 6 hours
Place a lid or foil loosely over your container and leave it to cool. During this time the coir will fully absorb the water and the substrate will cool down to room temperature. After 4 to 6 hours, put on gloves and mix everything thoroughly. The substrate should now be uniform, evenly moist and fully cooled.
4
Check the Field Capacity of Your CVG Substrate ~2 min
Field capacity is the ideal moisture level for your substrate. At perfect field capacity, your substrate creates the right humidity inside a closed monotub so that you do not need to open and water it constantly.
The squeeze test: Take a handful of substrate and squeeze it as hard as you possibly can. Judge what comes out.
Too Wet
A stream of water drips out. Add dry vermiculite and mix again.
Perfect
Only a few drops come out. This is exactly what you want.
Too Dry
Nothing comes out at all. Mist with water, mix and retest.
5
Add Spawn and Mix ~5 min
Add your colonized grain spawn into the monotub and break it up completely into small individual grains with no large clumps remaining. Then add approximately two thirds of your CVG substrate and mix everything together thoroughly until the spawn is evenly distributed throughout.
Work quickly. Minimize how long the substrate and spawn are exposed to open air. Sanitize your hands and all tools with 70% isopropyl alcohol before starting.
6
Add the Casing Layer ~2 min
Spread the remaining one third of your CVG substrate evenly over the top as a casing layer. This top layer protects the surface, reduces contamination risk and can improve pin set density. Gently press it down to eliminate air pockets.
Is a casing layer required? It depends on the species you are growing. For many grows it is not strictly necessary, but it never hurts either. I always add one since the benefits outweigh the minimal extra effort.
7
Colonization Conditions 5 to 14 days
Seal or loosely cover the monotub and move it to a warm, dark location. Avoid disturbing it during colonization as mycelium does not like being moved. Check daily for signs of white growth spreading through the substrate. Once the surface is fully covered in white mycelium and small pins (tiny white dots) begin to appear, you are ready to switch to fruiting conditions.
Temperature
21 to 24 °C
70 to 75 °F optimal range
Duration
7 to 14 days
Varies by ratio, temp and spawn health
Light
Dark
No direct light during colonization
Fresh Air
Minimal
Limited FAE until fully colonized
8
Fruiting Conditions and Fresh Air Exchange Until harvest
Once your CVG substrate is fully colonized and pins are forming, it is time to switch to fruiting conditions. The main trigger is simply removing the tub from the dark and placing it somewhere with ambient room light. Direct sunlight should be avoided, but otherwise light level does not matter much. If your monotub has holes plugged with polyfill or micropore tape, fresh air exchange happens automatically and you do not need to manually fan it. At perfect field capacity your substrate holds enough moisture on its own, so misting is usually not necessary either.
Temperature
20 to 23 °C
68 to 74 °F slightly cooler triggers pinning
Light
Any indirect
No direct sunlight, everything else is fine
FAE
Automatic
Polyfill or micropore tape holes handle this passively
Humidity
90 to 95%
Perfect field capacity keeps this stable without misting
First flush timing. Most setups produce their first pins within 5 to 14 days of switching to fruiting conditions. Harvest individual mushrooms just before or as the veil underneath the cap begins to tear. Do not wait until after the veil breaks as quality and shelf life both drop quickly after that point.
After each flush: Remove any leftover stems or dead material, lightly mist the surface and let the substrate rest for a few days. Most CVG setups will produce 2 to 4 flushes before yields drop off significantly.
FAQ
Frequently Asked Questions
Quick answers to the most common questions about mixing, hydrating and using CVG substrate.
CVG is a bulk mix of Coco Coir, Vermiculite, and Gypsum for growing dung loving species. To get the perfect cvg mushroom substrate recipe, you just mix these dry ingredients with boiling water. A proper cvg mix ratio provides the ideal environment for your mushrooms to thrive.
A mushroom substrate calculator helps you figure out the exact amounts of water, coir, and vermiculite needed. Using a reliable cvg calculator ensures your mix reaches the perfect field capacity without any guesswork. Simply input your total desired weight for precise measurements.
When mixing your bulk sub, finding the ideal spawn to substrate ratio is critical for fast colonization. Most growers prefer a cvg substrate ratio of one part spawn to two parts bulk. Use a spawn to substrate ratio calculator to perfectly scale your recipe for maximum yields.
Figuring out exactly how much mix you need for your bin is easy when you use a monotub calculator. A dedicated monotub substrate calculator tells you the exact volume required for your specific tub dimensions. This ensures an even three inch layer for optimal mushroom growth.
Perfect field capacity is the optimal moisture level where your bulk substrate holds maximum water without being waterlogged. Check it by grabbing a handful and squeezing firmly. Only one to three drops should fall out. If a steady stream drips, it is too wet for your fungi.
The standard coco coir vermiculite substrate ratio involves five hundred grams of coir to five cups of vermiculite. Adding a bit of gypsum perfects this cvg ratio by stabilizing the pH level. This balanced formula prevents clumping and gives your mycelium a perfect foundation.