Foraging for food is one of my passions. I take to it like others take to hunting or fishing, there’s just something about finding one’s own food that is deeply satisfying. So cultivating mushrooms is a little different; it involves taking found food to the next level. But it’s still fun to produce your own food, especially when that food is….a little strange.
Oyster mushrooms (Pleurotus sp.) are considered the “weeds” of the mycological world. They grow vigorously on a variety of media and are even used to mitigate pollution events. One company sells bags of oyster mushroom spawn for the sole purpose of soaking up and converting spilled oil. I don’t think I’d want to eat those mushrooms. The logical place to start then, is with a mushroom species which is super easy to grow and likely to compete with their prices at the grocery store, if you can find them.
The ubiquitous button mushroom, Agaricus bisporus, and maybe the shiitake are often the only fresh mushrooms available at the grocery store. The Agaricus masquerades in several forms: white button, crimini and portabello, but they’re all the same species. Some other species are available dried, but they’re expensive and often come from eastern Europe, where they’re picked from the woods. We hope they don’t misidentify. Oysters are just as good and I’m going to find out if I can easily and cheaply grow them at home.
About two years ago my daughter gave me an oyster growing kit and I decided to take the next step. I started out by ordering a bunch of growing bags. These are sterile plastic bags with breather patches to let air, but not other spores in. But I was put off by the methodology involving sterilizing a huge amount of straw. In the third world they do this by adding a chemical, which I didn’t want to do. The other option is to boil or steam the straw, which seemed daunting. I imagined dumping a bale of straw into an old drum and boiling it over a campfire. Then there was the preparation of agar petri dishes, building a sterile hood and all the other bother associated with sterile technique. I had better things to do.
This month my Fungi Magazine came to the rescue. In it was an article by Milton Tam describing in detail how to grow oyster mushrooms without sterile technique. At last I had an easy option! The key to this approach is to use easily available growing materials which are already (reasonably) sterile. The process takes advantage of the rapid growth of the Pleurotus mycelia (underground “roots”) to get ahead of any other colonizers. The growth medium is a combination of newspaper-based kitty litter (no, not used!) and vitamin-enriched alfalfa-based guinea pig food. Both these products, from the pet store, are packaged in sealed plastic bags and are, we assume, reasonably sterile. The kitty litter (the brand mentioned was Purina’s Yesterday’s News, but I got another brand) serves as the cellulose base and the guinea pig food provides a nitrogen source. The procedure is to mix up 4 cups of the newspaper-based kitty litter with 4 cups of dechlorinated tap water and let it sit for 10 minutes until the water is absorbed. Then add 1/3 cup of the guinea pig food and 1/2 to 3/4 cup of mushroom grain spawn and mix well. More on getting the spawn in a minute. The mixture is stuffed into a plastic bag. Cut some small (3/4″) slits in the bag for air and place in a dark, cool area (under 70 degrees if possible) and leave for two weeks. This time of year it’s too cold in the basement but as it warms up that will be the place to grow in.
After two weeks the mycelium should be visible as a network of fine fibers in the mix, sort of like tempeh. At this point the bag needs to come into the (indirect) light and warmth where it will soon pop out mushrooms from the slits you cut. Some sources say that fruiting is encouraged by placing the bag in the fridge for a day (a “cold shock”), so if I don’t see primordia–the tissue growth that precedes mushrooms–I’ll do that. The expected yield is 8-11 ounces. There will probably be a “second flush” of a few more ounces 10 days after the first. Keep the emerging ‘shrooms moist by spraying with water mist.
Economics: This is of course a fun hobby, so we shouldn’t think of it as a way to avoid grocery bills, but let’s see the numbers anyway. I spent about $33 on kitty litter and guinea pig food. The grain spawn came from Northwest Mycological Consultants in Corvallis, OR (503.753.8198) and cost $35 delivered to Maine. I got 7 lbs, and if you check around, this is a very good price. They don’t have a website, so you have to call them, and they often don’t answer their phones, so you have to leave your name and hang around for them to call back. So that total so far is $68. The grow bags were about 60 cents each. Check back in a few weeks to see what kind of yield I get so I can translate that $68 into pounds of mushrooms. This first batch, which is a double recipe because my bag is so big, ended up costing $3.86 for the ingredients and the bag. A quick scan of fresh oyster prices on line returned from $7.67 to $20/lb, so if I can get a pound out of this batch I’ll be happy as a mushroom in the rain.
My spawn strain is #497, Pleurotus columbinus, a pearl blue-gray oyster. I plan on mixing up a batch once a week so the mushrooms will be in constant supply. Anyway, that’s the plan! I fear that my spawn supply will outlast my rate of use, i.e., spoil, so stay tuned for the exciting updates.
Beware that some spawn companies specialize in mushrooms which are…shall we say, consciousness altering, (usually sold as mushrooms for “microscopic study”) while others cater strictly to customers interested in edible varieties. Some sell both types, but I feel more comfortable ordering from the edible-only folks.