If you love the taste of mushrooms but aren’t comfortable traipsing through the woods to forage for them, you should consider growing them in your own home. Many mushroom varieties, including popular ones like shiitake, oyster, and white button, can be grown with little effort on your part.
As you would with any other plant, you'll begin the mushroom-growing process with high-quality seeds or starts. With mushrooms, you’ll purchase either spores (the fungal equivalent of seeds) or spawn (the fungal equivalent of starts). Spawn are easier to work with, especially if you’re new to mushroom growing. Be sure to purchase your spawn or spores from a reputable site or garden supply store — you want to ensure you’re working with materials from a trusted source.
Although all mushrooms will grow well in sawdust or straw, certain varieties prefer different planting mediums. For instance, shiitake mushrooms prefer hardwood or hardwood sawdust. Oyster mushrooms prefer straw or coffee grounds. White button mushrooms prefer well-composted manure. If you’re using sawdust, make sure you're getting it from untreated wood.
Mushrooms grow best when placed in a cool, damp, dark spot, like your basement (or another underused dark room in your house). The key is controlling that spot's temperature and humidity. If you’re using straw or sawdust, you’ll need to sterilize it before planting in it to kill anything that might compete for nutrients with your mushrooms. Do this by placing a portion of the straw or sawdust in a microwave-safe bowl and dampening it with water. Microwave it on high for about two minutes or until there’s no water left. Work with small batches until you've thoroughly sterilized the entire planting medium.
Then, place the growing medium in a baking pan and place it on top of a heated grow mat or heating pad, setting the temperature to about 70 degrees Fahrenheit. Add the spawn to the medium using a sterilized utensil. Make sure the pan is located in a dark room to encourage the spawn to spread throughout the medium. It often takes about three weeks for the spawn to colonize it.
Once the spawn has propagated itself, you'll want decrease the temperature of the heating pad to anywhere between 55 and 60 degrees Fahrenheit. Then, cover the medium with about an inch of potting soil. Cover both the soil and the pan with a damp cloth. You may need to spray water on the cloth if it begins to dry out.
Keep an eye on your colony. If you notice any dark brown or green spots, remove them and toss them out. Make sure the mixture remains cool and moist throughout the growing process and keep the temperature below 70 degrees. For easier harvesting, you can also place a low-heat lamp near the planting medium to help the mushrooms grow upwards.
You’ll likely start to see mushrooms in about three or four weeks. To harvest them, wait until the caps are open and separated from the stems. Also, remember to rinse them before eating and cooking them, and store them in a paper bag in the refrigerator (but not for more than a week).
Growing Mushrooms in Coffee Grounds
Since coffee grounds are already sterilized during the brewing process, you may not need to sterilize them before you plant them. The added benefit of growing in coffee grounds is that they're full of the nutrients mushrooms need to survive.
Typically, you’ll need about 190 ounces of coffee grounds to grow 18 ounces of mushroom spawn. It’s best to use fresh grounds (i.e. brewed that day), so get some from your local café if possible. Place the grounds in a filter patch grow bag or a large, resealable freezer bag. Sterilize your hands and mix mushroom spawn into the coffee grounds, making sure they’re evenly distributed throughout the bag. Seal the bag tightly. Place the bag in a warm, dark location where it can maintain a temperature between 64 and 77 degrees Fahrenheit. Leave it alone for two to four weeks — or as long as it takes for its contents to turn white. As with the other growing mediums, you'll want to remove any dark brown or green spots from the grounds and toss them. Once the contents have become totally white, move the bag to a bright area (but still away from direct sunlight) and cut a hole in the top (or just unseal it, if you used a plastic bag). Use a spray bottle to keep the bag damp, spraying daily if necessary.
Growing Mushrooms in A Log
Believe it or not, growing mushrooms in a log is actually one of the most common ways to grow them at home. It’s the ideal growing environment for several species, including reishi, maitake, lion’s mane, shiitake, pearl, and phoenix oyster. You’ll want to choose logs from non-aromatic hardwood trees, such as poplar, oak, elm, and maple. The log should be about three or four feet in length and a foot in diameter.
To grow the mushrooms, you’ll first inoculate the log with birch plugs that have already been colonized by mushroom spawn. It’ll take about 50 birch plugs to colonize a log of the aforementioned size. Ideally, you’ll cut the log at least two weeks before inserting the plugs. Use a 5/16-inch drill bit to drill two inch holes all over the log, spacing them about four inches apart from one another. Use a hammer or mallet to tap the plugs into the holes. If you’re planning to store the log outside, use cheese wax or beeswax to seal the plugs afterward. Over the next year, the mushrooms will colonize the log and break through the cracks. If conditions are good enough, the mushrooms will continue to grow for years to come.