The Best CVG Recipe (Coco-Coir, Vermiculite, Gypsum): A Beginner-Friendly Guide
Share
CVG stands for coco-coir, vermiculite, and gypsum. This bulk substrate is popular because it uses accessible materials, hydrates easily, and supports vigorous, even colonization. This guide is designed for beginners using common home gear (bucket, kettle or stove, measuring cups) and basic clean-technique.
What You'll Need
Equipment
- Large food-grade bucket with a tight-fitting lid (or a large pot you can cover)
- Heat source: kitchen stove or kettle for near-boiling water
- Mixing paddle or large spoon
- Gloves and 70% isopropyl alcohol for wiping tools and contact surfaces
Ingredients
- Coco coir (650 g compressed brick)
- Fine to medium-grade vermiculite
- Powdered gypsum (calcium sulfate)
- Clean water (tap is fine if reasonably low in chlorine)
CVG Recipe (1 Coir Brick Batch)
| Ingredient | Amount | Notes |
|---|---|---|
| Coco Coir Brick | ≈ 650 g (1 brick) | Common garden/terrarium bricks work well |
| Vermiculite | ~8 cups (≈ 2 quarts / ~1.9–2.0 L) | Add a bit more if you prefer a fluffier texture |
| Gypsum (CaSO4) | ~1 cup (≈ 150–200 g) | Buffers pH and adds calcium/sulfur |
| Hot Water | ~4–5 quarts | Boiling for hydration & heat-treating |
Water formula: Multiply your coco brick weight (g) × 0.022 + 4.5 = cups of water. Or in metric: brick (g) × 52 mL + 1065 mL = mL of water. Always finish with the field capacity squeeze test.
Field capacity check: Squeeze a handful — a few drops should escape, not a stream. If water streams out, it's too wet. If nothing comes out and it feels dusty, it's too dry.
Step-by-Step Instructions
1 Prep & Sanitize
Wipe bucket (inside), lid, spoon, and your work surface with 70% isopropyl alcohol. Put on clean gloves. This reduces contamination risk.
2 Dry Mix
Place the coir brick in the bucket. Add vermiculite and gypsum. Lightly stir to distribute the dry components.
3 Add Hot Water
Bring water to a boil. Slowly pour ~4 quarts (reserve ~1 quart to adjust later) over the mix. As the coir expands, stir thoroughly to eliminate dry pockets.
4 Cover & Hydrate
Close the lid and let the mix sit for ~60 minutes to fully absorb.
Tip: Wrapping the bucket in towels helps retain heat and keeps the substrate in the pasteurization range longer.
5 Stir & Adjust Hydration
Open, stir well, and check moisture.
- Too dry: Add the remaining hot water in small increments.
- Too wet: Let the substrate breathe uncovered and stir occasionally to release steam.
6 Cool to Room Temperature
Allow the substrate to cool completely (often 4–6 hours). Hot substrate can kill or weaken mycelium.
7 Spawn (Inoculate)
Move to a clean area. Break up colonized grain spawn and mix evenly with CVG. Typical beginner rates are 10–20% spawn by volume (e.g., 1 part spawn to 4–9 parts CVG). Thorough mixing shortens colonization time and reduces contamination risk.
8 Incubate, Then Fruit
Incubate at species-appropriate temperatures (commonly 65–75 °F). Once fully colonized (substrate appears evenly white), introduce fruiting conditions: light, fresh air exchange, and high humidity.
Sterile Workflow Gear
Use cultures from agar to make grain spawn? Our automatic and hands-free sterilizers keep your workflow moving.
Scaling the Recipe
Use this quick table to scale batches while keeping the same ratios. Adjust water at the end to dial in field capacity.
| Batch Size | Coir | Vermiculite | Gypsum | Hot Water |
|---|---|---|---|---|
| Half Brick | ~325 g | ~4 cups | ~½ cup | ~2–2.5 quarts |
| One Brick (Standard) | ~650 g | ~8 cups | ~1 cup | ~4–5 quarts |
| Two Bricks | ~1300 g | ~16 cups | ~2 cups | ~8–10 quarts |
Tip: Coir bricks vary in density and water retention. Always finish with the field-capacity squeeze test.
Spawn-to-Substrate Ratios
| Spawn Rate | Ratio | Best For |
|---|---|---|
| ~20% | 1:4 spawn:CVG | Faster colonization, lower contamination risk |
| ~15% | 1:5.5 | Balanced for most setups |
| ~10% | 1:9 | More economical, slower colonization |
Higher spawn rates shorten colonization time but use more grain. Choose based on your goals and contamination tolerance.
Troubleshooting
| Problem | Cause & Fix |
|---|---|
| Too Wet | Substrate drips or pools water. Spread out, mix, and allow steam to escape; add a small amount of dry vermiculite if needed. |
| Too Dry | Handful crumbles, no sheen. Sprinkle in hot water in small increments and mix thoroughly. |
| Stalled Colonization | Often hydration, temperature, or low spawn rate. Verify field capacity, keep 65–75 °F, and consider raising spawn rate next time. |
| Contamination | Usually from unclean surfaces or handling. Improve sterile technique — gloves, 70% iso, wipe-downs, minimal talking/breathing over open containers. |
Clean Technique Essentials
- Gloves + 70% isopropyl alcohol for hands, tools, and contact surfaces
- Minimize airflow over open containers (use a still air box or, ideally, a laminar flow hood)
- Break up grain spawn thoroughly before mixing
- Close containers promptly after mixing
Quick Checklist
- Bucket with lid
- Coir brick (650 g)
- Vermiculite (~8 cups)
- Gypsum (~1 cup)
- Hot water (~4–5 quarts to start)
- Gloves + 70% isopropyl alcohol
- Mixing spoon/paddle
- Clean work surface
Summary: Hydrate coir/verm/gypsum with hot water, cover 60 minutes, stir, adjust to field capacity, cool fully, mix in clean grain spawn (10–20%), incubate, then fruit.
Safety & Legal Notice
This article is for educational purposes. Follow all local laws and regulations regarding fungi cultivation and species. Work carefully with hot water and practice basic lab safety.
