Tuesday, July 8, 2014

Growing mushrooms

Do you know how to grow mushrooms? Has the thought ever crossed your mind? If you're American, which is most of the readers, the thought "I could grow pot! Or Shrooms!" may have crossed your mind at one point in your adolescence. Quite a few people are in the dark about where mushrooms come from and I'm out of things to talk about this week. So here's a crash course in mushrooms.
  • Hyphae - The long filamentous structure of fungi.
  • Mycelium - Grouping of hyphae. This is the mold that people are used to seeing.
  • Substrate - The food. It's the compost or bread or whatever that gives the fungus nutrition. I've worked with plants and fungus, and this is the part where I think mushrooms get picky or temperamental. Plants need soil, or water if prepared right, to grow. What substrate you use for mushroom depends on the mushroom. Shiitake grows on logs, but doesn't grow on the compost mix used for Agaricus. Some mushrooms grow on specific logs. Some grow best only after forest fires. The common portabella mushrooms found in almost any American grocery store grow in a compost substrate of straw mixed with other nutrients needed.
Standard practice for large corporations or small home growers is to mix portabella mycelium with a cooked millet substrate. Millet is combined with gypsum and cooked for approximately 30 minutes. When that's finished, the mixture needs to be sterilized. A large industry would use an autoclave, but the smaller home version is a pressure cooker. This process kills any contaminants, notably any other molds that have gotten in that are unwanted. Stuff like trichoderma, mucor, or aspergillus which is either more "aggressive" than our portabellas or are potentially dangerous.
The culture starts out as a spore print. The mushroom is left to open and is placed on paper. It drops its spores onto the paper, and then is collected and grow on a petri dish. When the dish is fully colonized, chunks are taken out of it and placed into a 1-liter jar with the millet substrate, where the mycelium grows over and colonizes the millet.
When the millet is fully colonized, it's time to grow mushrooms. This is a two step process lasting a month. The millet is well mixed with compost and placed in an air controlled room. The CO2, humility, and temperature must be carefully monitored. Fungus breathes in oxygen and breathes out CO2, so if the level is too high it could kill it. When the compost is fully colonized, the second stage is placing a layer of peat moss on top. During this stage, fresh air is brought in along with a drop in temperature which triggers the fruting mechanism of the fungi. It thinks its going to die, so it makes the mushrooms in order drop its spores and continue its genes.
Done. Enjoy, and ask questions so I can clarify parts of it.

1 comment: