Larger-scale cultivation in plastic tubs with bulk substrate for higher yields. More setup, more harvest.
Advanced · 5-8 weeks to harvest
The monotub method scales up production using bulk substrate (coco coir, vermiculite, gypsum) colonized by grain spawn. It requires more preparation and sterile technique but yields significantly more mushrooms per grow cycle—typically 1-3 oz dried per tub.
A monotub is a large plastic storage tub (50-66 qt) modified with holes for air exchange. You fill it with a mix of colonized grain spawn and pasteurized bulk substrate, let it colonize, then fruit directly in the tub. One tub can yield 1-3 oz of dried mushrooms. Plan for 5-8 weeks total: 2-4 weeks for grain colonization, 1-2 weeks for bulk colonization, and 1-2 weeks for fruiting.
Start with sterilized grain (rye berries, whole oats, or millet) in quart jars or spawn bags. Pressure cook grain at 15 PSI for 90 minutes. Once cooled, inoculate with a spore syringe or liquid culture (1cc per jar). Let colonize fully (2–4 weeks). Shake jars at 30% colonization to speed up the process and ensure even growth. Fully colonized grain—completely white with no visible grain—is your spawn.
The most common bulk substrate is CVG: coco coir, vermiculite, and gypsum. Mix 650g coco coir (1 brick), 2 quarts vermiculite, and 1 cup gypsum (optional but improves structure). Pasteurize by placing in a 5-gallon bucket and pouring 4 quarts of boiling water over it. Close the lid and let sit overnight. Proper field capacity means the substrate holds moisture but doesn't drip when squeezed firmly.
Drill or melt 2-inch holes in your tub: 2 holes on each long side (4 total) about 4-5 inches from the bottom, and optionally 2 holes near the top for additional FAE. Stuff holes with polyfill or cover with micropore tape. Clean the tub thoroughly with isopropyl alcohol before use.
In a clean area, break up your colonized grain spawn and mix with bulk substrate at a 1:2 to 1:4 ratio (spawn to substrate). More spawn = faster colonization but higher cost. Mix thoroughly or layer (spawn-substrate-spawn-substrate). Level the surface and optionally add a thin casing layer of pure CVG on top. Close the lid and tape over all holes during colonization.
Keep the tub in a warm, dark place (75–80°F) for 7–14 days. The surface will turn white as mycelium colonizes the substrate. Don't open the tub during this phase—CO2 buildup is fine and actually helps colonization. The substrate is ready for fruiting when the surface is 75-100% colonized with white mycelium.
Once colonized, introduce fruiting conditions: remove tape from holes (or flip/crack the lid for more FAE), provide indirect light (12/12 cycle or ambient room light), and maintain humidity by misting walls if the surface looks dry. Temperature can drop slightly to 70-75°F. Pins (tiny mushroom primordia) should appear within 1–2 weeks.
Harvest when veils begin to tear by twisting gently at the base or cutting with a clean blade. Harvest the entire flush at once for best results. After the first flush, rehydrate by pouring water on the surface and draining after 6-12 hours (or float the substrate). Subsequent flushes will be smaller but can continue for 3–5 cycles. Total yields of 1–3 oz dried per tub are common.
Growing psilocybin-containing mushrooms is illegal in many countries and in most of the United States. Laws vary by state and locality. This content is for educational purposes only. Check your local and national laws before acquiring spores, equipment, or attempting to cultivate any controlled species. We do not encourage or assist in any illegal activity.
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