How to Build a Monotub for Mushroom Cultivation: Full Step-by-Step Guide
Learn to construct and use a monotub for growing mushrooms at home. Includes substrate prep, grain spawn, FAE systems, contamination prevention, and harvesting techniques.
Building a monotub is a cost-effective way to grow mushrooms at scale. This guide covers everything from construction to harvest!
Step 1
Gathering Materials & Tools
Essential Items:
- 64-quart clear plastic bin
- 1-inch & 2-inch hole saw drill bits
- Self-healing injection port grain bags
- Sterilized grain spawn (rye, millet, or wheat berries)
- Bulk substrate (manure-based or hardwood blend)
- 70% isopropyl alcohol
- Nitrile gloves and microfiber towels
Optional Upgrades:
- Fresh air exchange (FAE) fan
- Ultrasonic humidifier with hose
- Programmable cycle timer
Step 2
Constructing the Monotub
Follow these steps for proper hole placement:
- Mark positions:
- Lower holes (2-inch): 8.5 inches from base (2 per long side, 1 per short side)
- Upper holes (1-inch): 4.5 inches from base (3 per long side)
- Drill holes in reverse mode to prevent plastic cracking
- Deburr edges with a utility knife
Step 3
Preparing Grain Spawn
Inoculation Process:
- Sterilize workspace: Wipe surfaces with 70% isopropyl alcohol
- Inject spores: Use 3-5cc of spore syringe or liquid culture into grain bags
- Colonize: Store at 72-75°F for 14-28 days until fully white
Discard bags with green mold, sour smells, or excessive moisture—these indicate contamination.
Step 4
Mixing Spawn & Substrate
Substrate Recipes:
- Manure-based: 50% pasteurized horse manure, 50% coconut coir
- Hardwood-based: 80% oak pellets, 20% wheat bran
Layering Process:
- Sanitize tub: Wipe with alcohol
- Add substrate: Layer 1-inch substrate, grain spawn, and repeat
- Top layer: Finish with 1-inch substrate casing
A proper substrate-to-spawn ratio is crucial for success. Aim for 2:1 or 3:1 substrate to spawn.
Step 5
Colonization Phase
Monitor these conditions for optimal growth:
- Temperature: Keep at 72-75°F
- Humidity: Maintain 90-95%
- Light: Provide indirect ambient light (12h/day)
- Timeline: Allow 2-3 weeks for full colonization
Step 6
Fruiting & Harvesting
Triggering Mushroom Growth:
- Introduce FAE: Remove micropore tape from lower holes
- Mist daily: Maintain 85-90% humidity with distilled water
- Harvest:
- Psilocybe: Before the veil breaks
- Oyster Mushrooms: When caps flatten
Harvest mushrooms by gently twisting and pulling from the base. Don't leave stumps that could rot.
Frequently Asked Questions
Troubleshooting Common Issues
| Problem | Cause | Solution |
|---|---|---|
| No pinning | Low humidity/FAE | Increase misting/FAE |
| Side-pinning | Substrate shrinkage | Use black plastic liner |
| Contamination | Poor sterilization | Discard and restart |
Continue Reading
Beginner's Guide to Growing Mushrooms
A comprehensive guide for beginners starting their mushroom growing journey
How to Build a Monotub for Mushroom Cultivation
Step-by-step guide to building and using a monotub
How to Grow Mushrooms at Home
Complete guide to growing mushrooms in your home
