Colonization speed optimization — temperature, humidity, and genetics
39 replies · Cultivation
I've been tracking colonization times across different substrates, temperatures, and genetics for about 18 months. Want to share some data and discuss what actually moves the needle. Short version: temperature is the most powerful variable (75-80°F consistently outperforms cooler temps), grain type matters less than people think, and genetics is the biggest variable of all — fast-colonizing strains are worth selecting for.
Temperature is king. My data across 200+ jars: 65-70°F: 3-4 weeks typical 72-75°F: 2-3 weeks typical 78-82°F: 10-18 days typical Above 86°F: contamination risk increases significantly, mycelium dies above 95°F. A heat mat under a tub with a thermostat controller is the single best investment for colonization speed.
Grain type colonization comparison (my experience): Wild bird seed: fast (2-3 weeks at 78°F) Rye berries: slightly slower but very nutritious — great end colonization density Wheat berries: similar to rye Corn: slower, harder to work with Millet: fastest but smaller grain = more surface area = higher contamination risk if not sterilized perfectly. WBS is the best beginner grain — cheap, widely available, fast, and forgiving.
Genetics is the variable most people underestimate. A fast-colonizing isolate can cut 30-40% off colonization time vs. a slow one on identical substrate. If you're not doing agar isolation to select for fast rhizomorphic growth, you're leaving time on the table. The work of isolation pays back over dozens of grows.
CO2 management during colonization: contrary to popular belief, completely sealing jars during colonization is fine — CO2 builds up but doesn't harm mycelium. FAE is important during fruiting, not colonization. Overventilating colonizing jars by opening them introduces contamination.
35 more replies — forum posting coming soon.