Mushroom Farming, shiitake mushroom on a log
Michael R. Shea
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Several hundred logs, all 4 inches in diameter, 3 to 4 feet long and arrow-straight, lined the forest floor. Propped up against thin tree branches nailed between trees, they looked like little lean-tos, upright and at an angle. On tighter focus, the logs blossomed to life, each covered with shiitake mushrooms. This is mushroom farming. Steve Gabriel, the agroforestry extension specialist with the Cornell Small Farms Program and co-owner of Wellspring Forest Farm in Trumansburg, New York, bent down and trimmed a shiitake with a small pair of scissors and gently placed it in a large stainless bowl. “This is my kind of workday,” he said. “I’d much rather be out here, working with my hands, than indoors.”

“For most small farmers,” he said, “shiitake cultivation fits right in with other agriculture practices.”

Mushroom Farming: A Good Cash Crop

Early in the class, Gabriel pointed out the economics of mushroom farming. For many, the “cash crop” value of shiitakes is the biggest draw. If you don’t have to pay for labor and without factoring in the specifics of your property expenses (rent or mortgage, insurance, utilities), new shiitake growers committed to cultivating 400 logs a year could do quite well for just a few weeks of work each year.

By Cornell’s model, the new grower would take a loss the first year. He or she would have no sales and some small tooling costs. The following year, with a typical harvest on those 400 logs at a conservative sale price of $12 a pound, the second year could result in a $3,556 profit. By year four, if the grower maintains the workflow of starting 400 new logs every year, the profit jumps to a potential $10,132.

The Circle of Spore

Shiitake mushrooms were first documented thousands of years ago in Japan. Growing on downed “shii,” or the beech-like chinquapin tree, early agrarians realized that placing a log full of shiitakes near another downed log would result in that second log eventually growing the delicious fungi. With a little shiitake spore in the already colonized log, they were able to create a chain reaction.

Flash forward to the present day. You’ll find that the process for inoculating logs with shiitake, and later harvesting them, isn’t all that different. A fresh log is drilled, impregnated with mycelium and sealed over with wax; expect it to have a life of four to five years. This practice is labor intensive and largely at odds with modern factory farming techniques. So for small farmers willing to get their hands dirty, the reward is an incredibly high price per pound. Fresh shiitake runs anywhere from $10 to $18 per pound, depending on the market and your end-customer.

Mushrooms reproduce through spores. These are stored within the gills on their undersides. They recombine to produce the mycelium. This is the vegetative parts of the fungus that grow to make more mushrooms. In shiitake production, it’s the mycelium strands mixed into sawdust that are injected into the logs. These are what colonize the log and give rise to the mushrooms.

Mycelium Source

Ever wonder where the shiitake mycelium you purchase comes from? In a sterile lab, horticulturists dissect mushrooms and place a piece of the fleshy interior on nutrient-rich potato dextrose agar. It’s then incubated, and mycelium starts to form. Once it has matured, horticulturists cut the mycelium into small pieces and transfer them to sterile grain. Several weeks later, they transfer this grain inoculum to sterile sawdust, which is commonly known as spawn.

With spawn obtained, which you can get inexpensively online, there are four stages of shiitake cultivation to work through.

  1. Substrate acquisition: cutting down live trees in the spring for bolts, or 3- to 5-foot lengths, and buying spawn to inoculate them.
  2. Inoculation: the drilling of holes about 1.5 inches deep and 4 inches apart throughout the log, filling them with fungal mycelium, then sealing over the hole with premium food-grade cheese wax.
  3. Substrate colonization: the waiting game of one year to 18 months while the mycelium colonizes the log in your shaded mushroom yard.
  4. Mushroom farming production: the harvest, which involves “shocking” each bolt in a bath of cold water for 24 hours, then waiting a week for the mushrooms to bloom, at which point they can be collected for market.

Getting Started Mushroom Farming

Shiitake grow on a variety of wood species. In the Northeast, oak and sugar maple are ideal, with ironwood, musclewood and beech coming in next. In other parts of the country, check with your local extension service for recommendations. Woods like white ash, elm, evergreen, fruit and softwoods won’t get you too far. As we did a timber stand improvement on our place, we saved all the right-sized maples and oaks, noting that young trees are better than old.

Typically, mushroom farmers fell logs in the spring and inoculate right away. If you don’t have the time in spring, felling in winter is possible. If you go that route, make sure to stack logs off the ground and place them out of direct sunlight and wind so their moisture levels remain high. Since the mycelium colonize only the sapwood sections (the lighter outer layer) of a tree, you should select living trees with a bigger sapwood-to-heartwood ratio. The ideal size for logs is 4 to 6 inches in diameter. Why? Because they’re easier to manage and it optimizes the amount of sapwood. Length is not as important, but remember to keep the size manageable. It’s also important that the bark is intact. Any damage to the bark invites invasion from other species of fungi and allows for the loss of moisture.

If you opt to purchase pre-cut bolts, expect to pay $1 to $3 dollars a bolt. Keep in mind the guidelines you would use if you’d cut the wood yourself. Purchase only wood with bark intact. Ask the logger when the wood was cut and how it was stored. As always, be sure that whomever you purchase the wood from is managing the woodlot sustainable.

Inoculating Bolts

Once wood was acquired, we set up a high table that allowed one person to drill inoculation holes into our bolts, two people to inoculate and one person to wax over the filled holes. With the help of friends and family, and with work parties ranging from one to four helpers, we did 100 logs in about 40 hours. It was our first time, and I’m sure it can be done faster from now on. We also used a variety of different spawn to see which variety/wood combinations worked best at our place.

After all the work of felling, inoculating and waxing, the inoculated bolts were ready for their year-long rest in a laying yard. The most important feature of this resting place is that it be in permanent shade. Beneath the canopy of a coniferous forest that’s accessible by a tractor or vehicle is best. It’s a good idea to keep the logs near electricity and water for the purpose of inoculation and flushing them in the summer, unless you have a four-wheeler or you don’t mind the trek. We inoculated ours near the house and tractored them to a yard near a creek, which we use as our water source. Hindsight being 20/20, we now wish the mushroom yard was closer to our home and other farm projects.

Shocking Bolts

Forcing the bolts, or the act of causing the logs to “fruit” on demand by shocking them with cold water, is likewise labor intensive, but it’s the only way to get a sure and consistent crop. We did this in a nearby creek. However, because most of our spawn are both cold- and warm-weather dependent, we now just wait for the logs to flush naturally. It’s less work but makes for an unreliable business model. Shocking your logs on a schedule means you can have shiitake at predictable intervals, which is important to regular customers like grocers and chefs.

Mycelium will often be visible on the ends of bolts like thin white threads, which is a good indicator that the bolts are ready to be shocked. Bolts inoculated with cold weather strains may be allowed to fruit naturally in the colder months of October, November, March and April. In the warmer months of May, June, July and August, logs may be shocked in seven-week intervals, such that once the first set of logs is shocked, you can re-soak them seven weeks later. The number of “shocks” a summer depends entirely on region and weather. Most people get at least two flushes a summer, maybe three or even four, depending how far south they live. But temperature is the critical factor; if the summer gets too hot, the logs won’t flush, just as if the weather gets too cold.

The Fun Part of Mushroom Farming

In Gabriel’s yard surrounded by fruit logs, the appeal of the operation—beyond the great money they can produce for a small homestead—is apparent. There’s something meditative about the forest, working quietly, harvesting the fruits of one’s labor in a space that isn’t bulldozed or tilled or altered in any dramatic way. Off in the distance, we could hear Gabriel’s duck flock working on slugs in the garden, and the harsh morning sun was kept off our backs by the thick oak canopy.

“It’s very possible to make a living out here,” he said, “doing this—working with the forest instead of against it.”

If you’re inspired to get into the shiitake game, visit smallfarms.cornell.edu. You can also download the excellent guide offered on Cornell’s Specialty Mushroom Cultivation website; much of this article draws information from it. Gabriel has also written an excellent primer for the Cornell Small Farms Program. Lastly, inoculation tools and spawn can be found online at fieldforest.net.

This article on mushroom farming is from the summer 2019 issue of The New Pioneer Magazine. Grab your copy at OutdoorGroupStore.com.

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