How To Easily Grow Mushrooms In A Glass Jar

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Even experienced gardeners can find the thought of growing mushrooms a little daunting. With traditional mushroom growing methods, you need to research substrates and treat them with special liquids or drill holes in logs to create plugs. But it doesn't have to be that complicated. Here's an unexpected use for leftover coffee grounds around your home: You can grow mushrooms in a glass jar in your kitchen with said grounds and mushroom spawn. The easiest type of mushrooms to grow indoors are oyster mushrooms, which come in a range of muted colors, including blue, pink, yellow, and brown. Other mushroom varieties you can grow at home with more experience include spindly enoki or umbrella-like portabello.

Order your mushroom spawn online. About 2 ounces roughly fills a 1 quart Mason jar with mushrooms. Get 100 plugs of 2funguys Grey Dove Oyster Mushroom Spawn — that's a little over 6 ounces — for about $12. A 100-count bag of North Spore Organic Shiitake Mushroom Plugs costs almost $22. You'll also need 4 to 5 tablespoons of spent coffee grounds that are less than 24 hours old. If you don't go through that much coffee in a day, your local coffee shop will usually be happy to give you some. Your equipment and work surface need to be sterilized with 70% isopropyl alcohol to avoid contamination that could interfere with the growth of your mushrooms. Don't forget to wear gloves, too.

Start by preparing your growing jar and lid. The spores need to be covered, but also benefit from exposure to fresh air. Use an awl or nail to poke a few holes in the lid, then cover the holes with masking tape or micropore tape, which allows airflow. Dump your coffee grounds into the jar and then mix in the mushroom spawn. Place the jar in a dark, warm cabinet with a temperature between 64 and 77 degrees Fahrenheit. For accuracy, get a simple ThermoPro Digital Indoor Thermometer and Humidity Gauge for about $12.

The coffee grounds will turn increasingly white as the mushroom mycelium, a kind of fungi root system, colonizes them. When they're completely white, add another 4 or 5 tablespoons of spent coffee grounds to the top of the mixture, but don't stir it in. Put the jar back in the warm cabinet until the new grounds turn white. Repeat the process every few days until the jar is almost full of colonized coffee grounds.

When all the grounds are white, your mycelium is ready to start fruiting. Move the jar to a shady spot in your home with plenty of fresh air. Remove the lid and cover the jar with a damp cloth. Not keeping a humid environment is among the mistakes everyone makes when growing mushrooms at home, so spray the jar with water twice a day to keep it moist. All going well, you should soon see tiny mushrooms popping up. Every morning, they'll be twice the size they were the day before — they're ready to eat when they stop doubling in size daily.