Blue Oyster, Lion's Mane and Shiitake mushrooms. Mushroom Temperature & Substrate Guide: Oyster, Shiitake, Lion's Mane, and Psilocybe Species Ask ten experienced mushroom growers what the most important variable in cultivation is, and the majority will say the same thing: temperature. Not substrate. Not genetics. Not even sterile technique — though that matters enormously. Temperature. It governs every phase of a mushroom's life cycle, from the first thread of mycelium grow