Growing mushrooms at home can be a fun and rewarding experience. It’s also a way to become more self-sufficient, lessening your dependence on grocery stores and restaurants.
Mushrooms grow best indoors in a garage, shed, basement or garden cold frame where temperature and humidity can be controlled. The key is to keep the growing medium moist, but not wet.
Spawning
In the wild, mushrooms grow in the soil but most mushroom enthusiasts, including those growing at home, inoculate substrates with a blend of spores and other nutrient sources, usually sawdust or straw. This mix, called spawn, acts a little like the starter you use to make bread. It takes weeks for a thick white mycelium to completely colonize the substrate and begin fruiting.
Mushroom kits and spawn are available at most garden centers, home supply stores, online purveyors of mushroom growing supplies and from many independent mushroom growers. These items make it easy for beginners to grow oyster and other species, although some prefer to sterilize their own grain and culture — a process that requires a dedicated sterile workspace and the use of a pressure cooker or autoclave.
Once the mycelium has grown into all of the space within a bucket filled with substrate, it’s time for the incubation period. It may take up to three or four weeks, depending on the strain of mushroom and the temperature, for a full colonization of the substrate. The mycelium grows quickly in a cool, dark environment and is more likely to fruit in that kind of environment than in the heat of summer.
Some growers also inoculate blocks of spawn and other materials to grow mushrooms in the yard, on logs or stumps and in piles of wood chips in gardens. These kinds of mushroom cultivation are more complex and may require more than a single calendar year before harvest.
To inoculate a block of wood, for instance, a grower might soak a block of wood chips in boiling water and then inoculate it with a layer of first generation mushroom culture (grain spawn or wedges of mycelium). The block is then placed in a plastic bag and stored in the same way that you would store a kit. For a more hands-on experience, you can try making your own mushroom plugs. You’ll need a few quart-sized buckets, some hardwood dowels that can be sterilized in a pressure cooker and a packet of first generation mushroom spawn. Use the instructions that came with the spawn to see how to prepare the spawn for use and add it to a bucket of wood chips or sawdust.
Pinning
Mushroom growers use a process called pinning to induce mushroom formation from mycelial growth in the casing, but keep in mind that impacts yield and the quality of mushrooms. The pinning process takes about 18 to 21 days after casing begins and involves managing several environmental factors.
In order for a mushroom to begin pinning, it needs to have a high concentration of mycelium and adequate moisture levels. These conditions are best achieved by maintaining a growing environment where the air temperature is between 77 to 81oF, the humidity is between 90-95% and the CO2 concentration is between 0.3 to 0.08 percent. Ideally, a fruiting chamber is used to maintain these conditions.
After mycelium colonizes a substrate, it forms outgrowths that are called initials, according to the Pennsylvania State University Mushroom Fact Sheet. The initials then enlarge into buttons, which then enlarge to become mushrooms. During the pinning phase, the number of buttons increases as the mycelial growth reaches its maximum nutrient density. Often times, the initials will stall or stop producing when the conditions are not right. Generally, this happens due to a lack of moisture or the spores becoming exposed and susceptible to competing molds.
To prevent stalled pins, mushroom cultivators will often use a humidification system or supplemental watering to maintain the optimum conditions for pinning. Some species require more moisture than others, and it is important to know the specific requirements for the mushroom that you are cultivating. For example, oyster mushrooms may need a higher humidity level and more frequent air exchanges during pinning, while shiitakes might need to be cooled or have a drop in temperature.
In addition, mycelial growth must be managed during the pinning stage to ensure that it does not become too dense and prevent the development of mushrooms. The mushroom grower must also carefully monitor water levels and apply it to the substrate when necessary. It is important to do so before the surface of the casing dries.
As a result of these many different variables, each mushroom growing operation is unique and requires constant adjustments in the production process to produce high quality mushrooms. Embracing experimentation with new techniques, substrates and environmental conditions is key to learning how to maximize the production of a bountiful harvest.
Fruiting
Mushrooms grow by absorbing nutrients from organic matter and directing those nutrients to a reproductive structure called a mushroom, or fruiting body. Home growers can start with a single mature mushroom, mushroom spores or a mixture of the two called spawn (much like the starter you use to make sourdough bread). Once it’s mixed with other nutrient sources—like sawdust, straw or grain—mushroom spawn acts a bit like the yeast you need to make sourdough. It supports the growth of tiny, white, threadlike bodies known as mycelium, which take in nutrients and draw them from their environment. Mycelium takes about seven to ten days to sprout before it starts forming anything resembling a mushroom.
Once the mycelium has fully colonized the substrate, it’s time to get it ready for fruiting. To do this, the substrate must be sterilized, a process that requires soapy water, rubbing alcohol and a clean towel. It’s also important to make sure the container has a good seal, to keep out dirt and other unwanted substances. The next step is to poke holes in the surface of the substrate around six inches apart. This is called “pinning,” and it’s the way mushrooms break through their casings to begin forming their own little fruiting bodies.
After pinning, the substrate should be put in an environment that’s conducive to your chosen species of mushroom. That can include a growing chamber that you build yourself, an area in your basement or a cold room in the garage. In addition to temperature stability, humidity and fresh air, fruiting can be influenced by light. Most varieties of mushrooms prefer to be fruited with a normal daylight cycle—which may seem contrary to the ‘keep ’em in the dark and feed ’em shit’ joke most people have heard about them.
Most of the equipment needed for mushroom cultivation is readily available at local hardware stores. Most home growers buy a kit that comes with all the necessary materials and sterilization equipment, but if you don’t want to invest in a full-blown growing chamber you can still use a shed, garage or garden cold frame as your workspace. Just be sure to find a place out of direct sunlight so the mushrooms can get the full benefit of the natural rays of the sun.
Harvesting
Mushrooms don’t need soil or fertilizer to grow, but they do require a substrate. This is a material on which the mushrooms will develop and eat, including straw, sawdust, wood shavings or shredded paper. Most mushroom enthusiasts start by buying a ready-to-fruit kit, which typically comes with detailed instructions and sterilized substrate material such as straw or coffee grounds.
The kit will also include inoculum, which is either a block of sterilized grains such as rye or millet or a cluster of mycelium. Mycelium is the underlying tissue of a mushroom, and it’s what home cultivators use to inoculate their substrate. The process of inoculation is called “colonization.”
Once the mycelium has colonized the substrate, it’s time for “pinning,” which is when the fruiting bodies begin to appear. As a mushroom matures, it draws carbon dioxide from the air and releases spores that eventually sprout into the mushroom’s cap. Pinning is one of the most complex aspects of home mushroom cultivation, and it’s crucial that the fungi are pinned to ensure proper development.
In order to get the best results from their kits, home growers should follow the instructions carefully. For example, the mushrooms should be kept at a relatively cool temperature and protected from sunlight. It’s also important to avoid watering the mushrooms, as this can damage the growing material. In addition, it’s recommended that you avoid pulling mushrooms to harvest them. Doing so can damage the surrounding mycelium, which may then stop producing mushrooms. Instead, home growers should cut the mushrooms off at the base.
In addition to being a fun activity for families, home mushroom cultivation can provide a useful way to increase your food security. As with any new hobby, there is a learning curve, but the rewards can be tremendous. Just remember to be patient and follow the guidelines provided by the kit, which will help you get started on the right foot. With a little time, you could be enjoying fresh, delicious mushrooms right from your backyard! And who knows, you might even be able to use some of the mushrooms in your next recipe for a family dinner.
