Bury fresh oyster mushrooms in a bucket of damp grounds, wait a while, keep moist.
After several weeks, harvest your own homegrown gourmet fungus for free.
Most other species of edible mushrooms are so particular about their environment that growing them in captivity requires a lot of careful work beyond what most people are willing to attempt. Pleurotus Ostreatus, on the other hand, is such a thriving and eager producer that it can be “copied” in your own home with a simple non-sterile procedure.
You will need:
- A container — a 5 gallon plastic bucket is a good choice
- Coffee grounds — enough to fill the container halfway
- Fresh oyster mushrooms, about 2 ounces / 50g or more
- A spray bottle.
- Some recipes to make use of the results
Notes on source materials:
Your source mushrooms, at least in many American cities, can be bought at a grocery store or supermarket. They must be fresh, not dried, but they don’t have to be in perfect condition. In fact, when you can find some that have begun to round the bend just slightly, those are the ones you want. Some Oysters seem not to realize they’ve been cut and packaged for sale: if you look closely you will find the more exuberant specimens continuing to produce new primordia and even fully-formed stems and caps right off of their own dying bodies. These more virulent examples make excellent starting material for a home culture.
To obtain the necessary volume of coffee grounds, you can either save your own for a while or, better, half-fill your container with recently discarded grounds from a coffee house. If you explain and ask nicely, or just make an excuse about a compost project you’re working on, most coffee bars will allow you to take away some of their waste material.
It’s preferable to bring home a mass of very fresh grounds like this rather than use your own, because the mass will tend to be properly hydrated, undecomposed, and uncolonized by competitor organisms. Once you establish your Oyster colony you can continue to feed it with leftover grounds from your own kitchen any time.
Planting your own colony is easy
First, make certain the grounds are at a reasonable moisture level. If you can squeeze liquid out of a handful, they’re too wet. If a handful, when squeezed into a ball, won’t hold together for a second, that is probably too dry. Excess water will breed competitor organisms and restrict the respiration that your oysters need to grow (they expire carbon dioxide, as we do). Insufficient water will stunt or entirely prevent their growth.
Having checked the water content, simply make your container half-full with grounds, then scoop out a hole sufficient to bury your source mushroom in the grounds. Tear your source Oyster (gently) into several pieces and lay them in the hole, then cover lightly with grounds, not too deep. About an inch of grounds covering the mushroom is good.
Care and feeding
What we call a mushroom is only the surface part of the organism — its reproductive parts, in fact. Before producing actual mushrooms, the organism must grow its main body, known as mycelium, under the surface of its food source.
Maintenance of your Oyster colony is very simple. Keep a lid covering most or all of the container, but not closed tight. Keep the material inside moist by spraying with water now and then. Depending on where you live, water may be needed in the morning and evening, or less than once per day. You will need to experiment with how open or closed the lid is kept, to keep a humid, but not stale, environment in the container. Experiment also with the temperature, by keeping the container in different locations — some strains of oysters prefer a range of around 55-70°F / 13-21°C; some will thrive in a somewhat cooler or warmer range.
