CVG – Easy, Effective Beginner Substrate for Dung-Loving Mushrooms

What You’ll Need

• Substrate Ingredients:
  • Coco coir (650 g compressed brick)
  • Medium-grade vermiculite
  • Garden gypsum (calcium sulfate)
• Tools:
  • Large heat-safe mixing bucket with lid (5–10 gallon)
  • Kettle or large pot for boiling water
  • Accurate kitchen scale
  • Stirring utensil or gloved hands
• Pasteurization Equipment:
  • Thermometer (to monitor 60–80 °C range)
  • Towels or insulation to wrap the bucket

Why CVG?

CVG is lightweight, airy, and resistant to contamination. Coco coir provides structure and moisture retention, vermiculite helps keep the mix fluffy and well-aerated, and gypsum adds calcium and sulfur — beneficial minerals that buffer pH and support strong mycelial growth.

Unlike nutrient-rich substrates like Master’s Mix, CVG is low-nutrient and can be prepared via pasteurization rather than sterilization, making it more forgiving for new growers.

Best Mushroom Species for CVG

• Psilocybe cubensis – The most common choice for CVG; fast colonization and consistent flushes.
• Panaeolus cyanescens – Benefits from CVG’s airy structure and water retention.
• Copelandia spp. – Similar benefits to Panaeolus; thrives in a well-hydrated, airy bulk substrate.

Exact CVG Ratios

Note: This recipe yields enough CVG to fill a standard 66 qt monotub with ~3–4 inches of substrate depth when combined with grain spawn.

Pasteurization vs. Sterilization

Because CVG is low in nutrients, contaminants have a harder time establishing themselves. This means it can be prepared via pasteurization — heating to 60–80 °C (140–176 °F) for 60–90 minutes to kill most competitor organisms while preserving beneficial thermophilic microbes that help suppress contamination.

Sterilization is unnecessary for CVG and can even make it more vulnerable to contamination by wiping out these beneficial microbes.

Step-by-Step CVG Preparation

1) Break Up the Coir Brick

• Place the 650 g coir brick in your clean bucket.
• Sprinkle gypsum evenly over the top.

2) Add Vermiculite

• Weigh ~800 g of vermiculite and add it to the bucket on top of the coir and gypsum.

3) Pour in Boiling Water

• Boil ~4 liters of water and pour evenly over the dry mix.
• Ensure all areas of the coir are wetted — pour slowly in circles.

4) Seal & Insulate

• Put the lid on the bucket.
• Wrap the bucket in towels or blankets to retain heat.
• Let sit for at least 60–90 minutes — temperature should remain in the pasteurization range.

5) Mix Thoroughly

• After pasteurization, open the bucket and stir the mix thoroughly to ensure even hydration and break up any clumps.

6) Field Capacity Check

• Squeeze a handful — only a few drops of water should escape.
• If too wet: add a bit more dry vermiculite and mix.
• If too dry: add hot water in 100 mL increments and mix.

Using CVG with Grain Spawn

1. Allow the CVG to cool to room temperature before use.
2. Mix fully colonized grain spawn into CVG at a ratio of 1:1 to 1:2 (spawn:substrate) for fastest colonization.
3. Spread evenly in your monotub or fruiting container and level the surface gently.
4. Cover and incubate until surface is fully colonized before introducing fruiting conditions.

Prefer Pre-Made CVG?

We offer pasteurized, ready-to-use CVG substrate for fast and clean setup. Order pre-made CVG here.