The spawn run

This stage gave the site its name. After inoculation the spawn sends white threads of mycelium through the substrate. It needs warmth and little else: suppliers quote about 65 to 77 F. A full bag makes its own heat, so the middle runs warmer than the room, and the core should stay under 90 F.

Timing depends on the species. Oysters on straw are usually white in 10 to 21 days, pink oyster often sooner. Lion's mane takes about two to three weeks, and its mycelium is so fine that the block can look barely colonized. Shiitake needs about 12 weeks and turns brown before it is ready. The growth time chart lists each variety.

This is also when contamination shows. Healthy mycelium is white and smells fresh or faintly sweet. A patch that turns green, blue-green, black or orange, or a wet area with a sour smell, is a competitor and not the mushroom. Mold on a kit or block shows how to tell them apart and when a block has to go.

Ready to move on when: The substrate is white with mycelium on all sides, or the first pins appear at the holes. Shiitake blocks have also turned mostly brown.