How to Grow Mushrooms Indoors

Lead Image
  • 4-8 hours
  • Intermediate
  • 20-500
What You'll Need
Growing medium
Spores
Microwave
Microwave safe bowl
Shallow pan with a large surface area
Dark warm area

Mushrooms are exceptionally resilient plants, and can thrive in many kinds of environments. To grow mushrooms indoors, you either need a kit or set up your own medium. Managing the growing conditions carefully is important, so the preparations can be complicated. Once you get everything ready, though, the mushrooms will grow relatively quickly, so this process can end up being highly cost efficient over the long term, and since mushrooms are both delicious and great for you, this kind of gardening can be an investment in both your dining and your health. Here's a step by step guide on how to grow mushrooms indoors.

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Step 1 - Choose the Right Mushroom to Grow

Three of the easiest types of mushrooms to grow at home are oyster, white button, and shiitake. These are grown using a similar method, but the ideal growing medium differs. Oyster mushrooms grow best in straw or coffee grounds while shiitakes grow best on hardwood sawdust. The button mushrooms grow best in composted manure. These different mediums reflect the different nutritional needs of each species; on top of that, each of these three species can be grown readily enough in sawdust or straw. Make sure that if you use sawdust, it is from untreated wood.

Step 2 - Purchase Mushroom Spawn

Mushroom spawn is sawdust saturated with mushroom mycelia- essentially the root structure of the fungus. It is used much like plant seedlings to facilitate growth. High-quality mushroom spawn can be purchased from several online retailers, gardening supply stores, or specialty organic living stores. Make sure to buy spawn rather than spores. Some retailers will also sell spores, which are more akin to the seeds of plants (rather than seedlings). Growing mushrooms from spores require time and are best suited for a seasoned mushroom grower.

mushrooms growing on substrate

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Step 3 - Sterilize the Growing Medium

If you are growing mushrooms in straw or sawdust, it will be vital to sterilize these growing substrates before inoculating with the spawn. This is done to kill off any micro-organisms that could compete for the resources with the mycelia. To sterilize the medium, place it in a microwave-safe bowl and add enough water to make the straw or sawdust damp. Place the bowl in the microwave and heat on high for two minutes, or until the water has boiled off. This kills off any microorganisms, leaving the substrate safe to receive the mushroom mycelia. You may need to work in batches in order to sterilize all of the straw or sawdust.

Step 4 - Heat the Medium

The mycelia in your mushroom spawn need to spread into the medium thoroughly before producing mushrooms. A warm temperature encourages the spread of the spawn. After the correct choice of substrate best suited to your mushroom species, place a few handfuls of it into a baking pan. A shallow pan with a large surface area will provide the most room for your mushrooms to grow. Mix the spawn into the substrate with a sterilized utensil. Place the baking pan on a heating pad set to 70°F (21°C). This is the ideal temperature to encourage growth. You can also try simply placing the pan in a warm area at your home. Leave the setup in a dark environment, such as a cabinet, for about three weeks. This will allow the mushroom mycelia to permeate the substrate.

mushroom growing substrate

Step 5 - Place the Substrate Into the Proper Environment

After two weeks, check the substrate to see if it has been fully colonized—the substrate should be entirely covered with what looks like white fuzz. This may take between two to four weeks. If the substrate is colonized, you can move the pan into an environment that is dark and cool (about 55°F or 13°C). A basement usually works well for this, but a cabinet or drawer in an unheated room will work in winter. If you notice any dark spots of green or brown (like what you might see on moldy bread), remove these areas from your substrate and throw them out.

Cover the substrate with a handful of potting soil and spray the entire mixture with enough water to dampen it thoroughly. You can place a damp towel over the pan to prevent moisture loss if desired. Consider placing a low heat lamp near the pan. This simulates the sun, which can help the mushrooms orient themselves and grow "up," making them easier to harvest. The mix should be kept moist and cool as the mushrooms grow. Check it periodically and spray it with water as necessary. The mushrooms will prefer a cooler environment, but the key is just not to let them get too hot. If the environment is below 70°F (21°C), then your mushrooms should grow fine.

Step 6 - Harvest Your Mushrooms

hand harvesting mushrooms

In about three weeks, you should start seeing small mushrooms appearing. Continue to keep their environment moist, cool, and dark to encourage their growth. When the mushroom caps separate fully from their stems, they are ready to harvest. You can pluck the mushrooms out with your fingers, but this risks damaging the newly developing fungi beneath the surface. Instead, use a sharp knife to cut the mushrooms at the base of the stem. It's best to rinse the mushrooms before cooking or eating. You can store harvested mushrooms in a paper bag in the refrigerator for up to a week.

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