Ah, mushrooms. For the wild mushroom hunter, making a fungi foray into a forest erupting with golden chanterelles, bursting with radiant oyster mushrooms, and scattered with black trumpets is like finding heaven itself. Days like these aren’t typical, however, and when you have a hankering to cook fresh mushrooms, you’ve probably found that most appetizing mushrooms – from morels to shiitakes – fetch a high price at farmer’s markets and specialty shops. But fortunately there’s another way to procure delectable gourmet mushrooms: grow them yourself.
Shiitake mushrooms, Lentinula edodes, have been grown in Japan for over 2,000 years. Shiitake are low in cholesterol, high in B vitamins, and have an exquisite taste. Their popularity as a valuable gourmet mushroom, as well as their reputation for having health benefits, is growing in this country as well. To supply the burgeoning market for shiitakes, forest owners in the United States are cultivating them in their woodlots as an agroforestry crop.
The name shiitake means “mushroom of the oak,” but shiitake mushrooms will also grow on sugar maple, hophornbeam, ironwood, alder, poplars, and yellow birch. Still, the mycelium’s favorite food for producing a flush of lovely brown shiitake caps is oak, either white or red.
Growing shiitake mushrooms as a forest product takes a bit of brawn and mycological know-how, but if you have a fondness for fungi and some hardwoods in need of thinning, this might be your most satisfying side business yet. That’s what shiitake grower Ithaca Farmer’s Market and to several area restaurants. With their forest mushrooms in such high demand, they plan on expanding their production. Each log inoculated has the potential of re-flushing for three years or more. According to Sierigk, “depending on the size of your logs, you can expect about a pound of mushrooms per log per year.”
Although Sierigk recommends starting small until you get the hang of it, Teresa Vanek and Brant Welch of Cornell Cooperative Extension, it’s okay to harvest logs as late as March for an April inoculation.
You should not inoculate right after cutting. Tree sapwood contains natural defenses against fungal invasion, including phytoalexin-like compounds called coumarins, that accumulate in the vicinity of wounding within 24 hours and continue increasing in concentration for the next few days. Because of this, it’s best to wait a minimum of three days to allow the compounds to disperse before inoculating the logs. “The rationale is to wait a week or two after harvest for antifungal agents in the logs to decline,” Ochterski said. Don’t wait much longer than that, because you want to make sure that other fungi don’t get a head start.
You can experiment with fall cutting and inoculation. Ochterski stresses that “there’s still not enough information on the physiology involved or the timing of harvests.” Growers in northern climes have had success inoculating as late as October. In any case, you should avoid the hot months of summer.
Mushroom Spawn
Shiitake mushroom spawn can be ordered from a specialty mushroom farm online or through the mail (see below for sources). Those with a mycological touch can even raise their own. Spawn generally comes either impregnated in wooden dowel plugs, in liquid form, or mixed with sawdust. The spawn is mushroom mycelium, the threadlike, non-fruiting part of the fungus that colonizes a log and eventually bears mushrooms. If mushrooms were apples, the mycelium would be the tree they grew on. The mycelium will eventually invade an entire log, showing white at either end when the log is fully colonized. Just prior to fruiting, a flush of small nodes, called pins, will be seen under the bark before the mushrooms themselves emerge.
The whole process from inoculation to fruit will take as little as four months or more than a year, depending on the strain of mycelium used, the weather conditions, and the moisture in the log. Several strains of shiitake are available for purchase: cold weather, warm weather, and wide range. Most growers recommend trying all three strains to determine what works best for your area and your market.
Inoculation
Plugs and sawdust are the most common inoculation techniques. For plugs, use a 5/16-inch bit to drill holes that are one inch deep, then gently hammer in the plugs. If using sawdust, use a 3/8-inch drill bit and drill to a depth of 11/4 inches before pressing in the sawdust. Plugs are easier to handle and apply, while sawdust produces better colonization if it’s kept moist. In either case, holes are generally drilled at 10-inch intervals down the length of the log. Spin the log to provide a gap of two inches between rows, and stagger the holes from one row to the next.
Many growers seal the holes with melted paraffin wax, which helps hold moisture in and keep wild fungal invaders out. Some growers also seal both ends of their logs for additional moisture retention. Use a wood moisture meter to monitor your logs for proper moisture content: between 35 and 45 percent is optimal for a successful harvest.
Stacking Logs in a Bedding Area
The bedding area for logs that have been inoculated with mushroom spawn should be well shaded and protected from wind, which will dry the logs. To conserve moisture in your logs, stack them close together and close to the ground, with space for minimal air circulation underneath. Choice bedding areas include hemlock and spruce stands, under hardwood trees, or even under shade cloths. A criss-cross, box pattern works well, as does slope-stacking down a hill in a cribwork. Some growers prefer to string a strong wire between two trees and lean the logs against the wire from either side, creating an X pattern. This method works well for ease of picking, but isn’t best for maintaining moisture balance in the logs.
Preparing For Harvest
Watering at regular intervals – weekly in drier areas where a drenching rain hasn’t recently occurred – is critical. You can either bring water to the logs or the logs to water. Some growers use 500- gallon livestock tanks, a pond, or a creek. You should soak your logs for 24- to 36-hour intervals – or until the logs stop forming bubbles and show signs of complete saturation. If you are going to use a soak tank, you’ll probably need a tractor to move heavy wet logs. The alternative to a soak tank is to use some form of irrigation or overhead watering system to drench the logs in place.
Soaking logs can force fruiting once mycelium is visible on log ends, or when pinning has occurred, but isn’t recommended once the mushrooms are visible. At this point, indirect sunlight can be beneficial to help fruiting. Some growers pound on their logs with a heavy bar to help encourage fruiting.
Because of the high moisture levels required for fruiting, mushroom bedding areas need some sort of control to prevent slugs from eating the budding fruit. Options include a gravel ground cover throughout the bedding area, pans of beer to drown the gastropods, or a circle of iron oxide that is refreshed as needed to create a barricade. Sierigk and other growers employ all three methods.
Once the mushroom caps begin to emerge, you may need rodent deterrents to keep chipmunks at bay.
The Harvest
At full fruit stage, the shiitake has a cap that is maroon-brown and speckled with lovely gem-like dots around the rim. Different strains vary to some degree, so learn to properly identify them. Gently break the stems off the logs and place them in cardboard boxes or paper bags. Once picked, the mushrooms will only stay fresh for a couple of days during hot weather. With refrigeration, they can keep for two to three weeks. If you can’t bring your crop to market in time, the mushrooms can be dried in a dehydrator or on screens in a greenhouse and packed for later sale. Dry shiitakes reconstitute well and still command a good price.
Establishing your market is best done prior to harvest. Try forcing a log or two ahead of time in a soak tank and taking these mushrooms to nearby restaurants, farmer’s markets, or specialty stores as samples. Fresh shiitake sell for about $16 a pound, depending on your area. Wild mushrooms, such as chanterelles, black trumpets, and hen-of-the-woods (maitake), go for around the same price. Whether you’re collecting mushrooms in the wild or farming them in your woodlot, you should never put mushrooms into plastic bags or they will quickly rot.
Whether you intend to grow shiitake mushrooms on a large scale or just for your own table, the process requires some work and plenty of patience, but the rewards are delectable. While the extravagant health benefits attributed to homegrown shiitakes – they’re said to boost the immune system, regulate diabetes, and combat cancer – are not scientifically proven, one thing is for sure: they’re all natural and very tasty.
Mushroom Spawn & Supplies
Mushroom Harvest
PO Box 584, Athens, OH, 45701
Phone: (740) 448-7376
Fax: (740) 448-8007
Email
Mushroom People
560 Farm Road, Summertown, TN, 38483
Email
Order Phone: (800) 692-6329 11-6 p.m. CST, M-F
Fungi Perfecti
PO Box 7634, Olympia, WA 98507
Phone: (800) 780-9126 / (360) 426-9292
For Further Reading
Growing Shiitake Commercially, by Bob Harris
The Mushroom Cultivator, by Paul Stamets and J.S. Chilton
Shiitake Grower’s Handbook: The Art and Science of Mushroom Cultivation, by Paul Przybylowicz and John Donoghue
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