Materials for Mushrooms
Logs aren’t the only way you can grow your own gourmet mushrooms.
if you think logs are the only way to grow your own gourmet mushrooms, think again.
Growing mushrooms is an area of food production that intrigues and mystifies the home grower. While mushrooms are treated like a vegetable in our kitchens, their cultivation is like nothing that comes out of our gardens. Mushroom cultivation can be particularly appealing to sustainability conscious farmers wanting to complete a closed-loop system of production. In the farm ecosystem, fungi play an important role of decomposing materials and providing nutrients to other organisms. When that fungi is also an edible mushroom and the material it decomposes (the substrate) is part of our waste stream, that can make growing them even more exciting.
“A lot of things that we throw out are cellulose-based that many mushrooms can degrade into compost,” says Willie Crosby, co-founder of Fungi Ally, a mushroom farm in Hadley, Massachusetts, which grows mushrooms for sale and educational purposes including agricultural waste products, such as soy-bean hulls and sawdust, and materials found in the home, such as cardboard and baby diapers — yes, baby diapers.
“We typically feel comfortable growing mushrooms on these things,” Crosby says. “The only thing to be concerned about when growing mushrooms is heavy metals because mushrooms hyperaccumulate heavy metals.”
If you want to start growing mushrooms, think beyond log culture, which, while popular, can be labor and resource intensive. Instead, turn to one of the following substrates for cultivating your own “mushroom garden.”
1. Toilet paper rolls
Toilet paper rolls — with the toilet paper still on — while not completely making use of the waste stream are a great substrate for beginning mushroom growers because they are inexpensive, readily available and, most importantly, a material high in carbon.
“With materials that have higher nitrogen content, you have to be more sterile,” Crosby says, but with materials such as toilet paper that have a higher carbon to nitrogen content, you don’t have to worry as much.
While paper products support many wooddecomposing mushrooms, oysters are a good place to start if you are new to the practice because they are generally forgiving of imperfect environments.
To grow mushrooms on a toilet paper roll, dip the roll in boiling water first to pasteurize it. Depending on the material, mushroom growing substrates generally need to be either pasteurized (heated to between 140 and 170 degrees Fahrenheit for two hours) to kill some microorganisms, or sterilized (heated to 250 degrees at 15 psi in a pressure cooker or autoclave) to eliminate the presence of microorganisms, Crosby says. For toilet paper, dipping in the boiling water until saturated suffices. To inoculate, place the roll in a tin tray filled with sawdust or grain spawn and fill the tube with spawn, as well.
Because this quick, beginner-friendly method uses few materials and produces mushrooms fairly quickly within two weeks, it’s a great way to introduce children to mushroom cultivation.
2. Coffee Grounds
Not much research has been done on growing mushrooms in coffee grounds, so while using this substrate might require some experimentation, it’s well loved, especially by those who have ready access to coffee shops in urban areas.
“Looking at what is being thrown away in a community and how can it be used, that’s a lot of the attraction of using coffee grounds,” Crosby says.
With coffee grounds, you can skip the pasteurization step; the brewing process takes care of that for you. However, you probably need to aerate the grounds; a substrate that is overly wet can inhibit mushroom growth. The growers at Fungi Ally mix in half sawdust to boost aeration. Again, stick with the forgiving oyster mushroom spawn for this substrate. When it’s sited in a reasonably dark and humid environment, you can expect a harvest in about a month.
3. Corn Cobs & Husks
According to Paul Stamets, author of the book Growing Gourmet and Medicinal Mushrooms, the cell walls of corn cobs and husks are a uniquely attractive environment for cultivating mycelium, the network of white fibers that is the precursor to mushrooms.
While growing mushrooms on corn cobs can be as simple as inoculating the cobs you just used to make corn stock, there are some considerations to keep in mind. Mushrooms produce better if the cobs are ground to 1- to 3-inch pieces. Also, pasteurization (boiling them for that stock) is all you need for clean cobs, but if any kernels are left on, you might need to sterilize to rid them of contaminants.
Oysters are another natural choice for this substrate, but other biomass-loving mushrooms, such as shiitake, have potential if you want to experiment.
4. straw
Straw — particularly wheat straw but also that of rye, oat or rice — is another forgiving substrate for the home grower who wants to grow oysters or wine cap stropharia. Plus, it’s cheap and readily accessible.
Straw can be pasteurized on a small scale by stuffing a pillowcase or feed bag with the material and submerging it in boiling water. Alternatively, there are unpasteurization methods that involve soaking the straw for a longer period of time (18 to 20 hours) in a solution of water and horticultural lime or wood ash. While this might be a good alternative for growers who don’t have the means to heat large vats of water, mushroom-spawn supplier Field and Forest Products does note that it requires a higher inoculation rate.
Straw provides more instant gratification over other popular substrates, such as wood chips, because the mushrooms digest the material more quickly, thus resulting in a more immediate harvest. Chopping up the straw prior to inoculation can speed up the results even more, providing a harvest in as little as eight weeks. The material continues to fruit for several months, decreasing in yield with each fruiting.
It’s a great material for no-till gardeners looking for a simple, passive way to increase the amount of organic matter in their garden beds.
Unlike some of the above substrates, you need to exercise a little more awareness with straw. When purchasing, be aware that you aren’t getting hay instead, as water-damaged hay isn’t good for mushroom growing. Also, pay a little more attention to the growing environment if it’s indoors. According to Field and Forest Products, a room with a temperature of 65 degrees, 90 to 95 percent humidity, and 10 to 12 hours of light is ideal. However, if you can give the mushrooms what they need, straw rewards you with plentiful, high-quality mushrooms.
5. SAWDUST
Compared with the other simpler-towork-with substrates, sawdust readily expands the types of mushrooms you can grow to include lion’s mane, nameko, maitake, oyster, reishi and shiitake. However, using it is for experienced mushroom growers who have acquired more advanced technique.
First, sawdust must be sterilized instead of pasteurized before use, which requires additional tools and equipment that might not be available to the home grower. “With the materials that have higher nitrogen content, you have to be more sterile,” Crosby says. “Sawdust becomes a lot more difficult to grow because of the fungi in the air (mold) that will eat those things.”
To reap a harvest, Stamets says you should mix it with a fruiting substrate, such as wood waste, seed or nut hulls, soybean roughage, tea leaves or one of the other substrates discussed in this article. He recommends mixing with various size wood chips in order to create an ideal mushroom habitat and sticking to quickly decomposing softwoods, such as alder, cottonwood and poplar, which better resist disease and help accelerate the mushroom life cycle. Stick to growing indoors, as sawdust is prone to contamination by competitor species.
If you try sawdust, it doesn’t necessarily have to be a DIY endeavor. You can purchase ready-made sawdust blocks. In the end, you get a harvest more quickly than if you were to grow on logs, albeit with mushrooms that have less of a meaty flavor.
6. WOOD CHIPS
If you intend to grow mushrooms outdoors, the next two substrates are ones to consider.
Wood chips turn any area, including your vegetable garden, into a mushroom-growing space, letting you pick blewits and wine caps among your tomatoes and squash. Wood chips provide a lot of flexibility because you can inoculate the bed at any time from early spring to early fall, though starting earlier in the growing season will result in a greater harvest.
When growing outdoors, Stamets recommends carefully considering the area
where you plan to site your bed. Locating it on the shady north side of a building or along a wall where condensation forms provides a distinct advantage over sunnier, drier locales. Also, avoid areas where competing species, such as wild mushrooms, are established.
While you can often get free wood chips from local tree-cutting services, do your best to learn where the chips came from. Trees that were located alongside busy roadways could have absorbed heavy metals, which then accumulate in the mushrooms. For best results, Stamets also recommends against mixing wood sources and sticking to softer deciduous woods. In general, the fresher the wood chips, the better.
7. Stumps
If you want a more natural setting for your mushrooms, consider growing on stumps. They are a great option if you own or have access to land with felled trees. It uses wood that has little to no economic value, and it accelerates the breakdown of the stumps. Stamets even notes that by inoculating stumps, you can help prevent the spread of certain diseases or parasitic fungi that in certain regions kill live trees.
The key to stump culture is inoculating before wild mushrooms take over, preferably in the spring for the
longest growing season. While all stumps can be inoculated, the ones with smaller diameter produce mushrooms more quickly — as little as 8 weeks — and the ones with larger diameter produce longer — as long as several years.
You can inoculate a stump numerous ways, so take your pick or play around to find the method that works best for you. You can drill into the flat surface of a stump, much like you would with log culture; girdle the sides with a chainsaw; or cut out chunks from the side, stuff with spawn and replace the chunks to the body of the stump. You can find details of these techniques in Growing Gourmet and Medicinal Mushrooms or through an online search. When it comes to stump culture, it’s best to stick to native mushroom species. Maitake and reishi do particularly well.
if you want to start growing mushrooms,
think beyond log culture, which, while popular, can be labor and resource intensive.
In the end, the type of substrate you use depends on what mushrooms you want to grow, the amount of effort you want to expend reaping your first harvest, and the materials available to you. Consult your spawn supplier to determine the best substrate for your preferred mushroom — or the best mushroom for the substrate you have.
Before you know it, you’ll be savoring some of the most flavorful and interesting mushrooms that no grocer can provide.