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Growing Shiitake Mushrooms: Step-by-Step Guide to an Agroforestry Crop

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.

mushA.jpg
Mushroom spawn comes in a variety of forms. Two of the more common are wooden dowel plugs, above, and a sawdust mixture, below. Photos by George Vaughan.

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.

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A criss-cross log pattern, below, works well. The traditional X pattern, above, makes harvesting easy but isn’t the best position for maintaining moisture balance in the logs. Photos by Angela Cannon-Crothers.

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

Discussion *

Jul 29, 2015

I am new to growing shiitake mushroom and was wondering, how many lbs of mushroom can you expect off of a log? I know it depends on temperature and moisture, but from all I read, the ideal temp is between 50-80 f and not to over water your logs. If anyone could help me please let me know. Thanks.

Daniel Dykes
Jan 26, 2014

I live in the Caribbean with average temperatures of 30 degrees Celsius…I have no knowledge of growing mushrooms and would like some advice on the best method to use growing the Shiitake mushroom for hot climates….

Would you suggest that I purchase the inoculated logs and see how they perform and maybe a few more strains of mushrooms that may perform in this weather…..I want to start small and get to learn as I go along with all of your assistance..ie type of structure needed to grow indoors etc

I have a small area of about 22 feet in length and 17 feet in width…..how many pounds of mushrooms on average can these logs produce?

Thank you for the wonderful article and look forward to hearing from you.

Kind regards,

Andrew Waithe

Andrew Waithe
Sep 11, 2013

Nice article, thank you.  Would you be willing to comment on using stumps for growing shiitake?  What time of year is best for felling trees and how long after for inoculation, how much stump should be left, inoculate from the top or from the sides through the bark .... ?

John
Aug 23, 2013

Good article on growing mushrooms, didn’t know that Perlite for mushrooms is used to cultivate it.

Az
Oct 10, 2010

Would appreciate suggestions for abeginner to raise mushrooms in Alaska

jim leach
May 11, 2010

Thanks for the info - great.

After the mushrooms have been picked, how do we propagate the next set of logs? Do we just cut the mycelium and put it in the new logs?

LHurst
Apr 23, 2010

just beginning to actively grow my own shiitake, I have a successful, robust garlic farm, and am excited to begin this new endeavor, wish me luck

lisa robertson
Apr 16, 2010

inoculated logs last spring. lots of mycilium showing on logs and bark splitting in spots. theres a few very small shrooms starting to pop. temps are in 60’s day,30’s night. what is the optimum temp. to force these logs to fruit. could i bring them inside after soaking?

steve schoenmann

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