Cultivating specialty mushrooms
While classified as produce, they aren’t a vegetable, herb or fruit. Mushrooms – edible fungi – aren’t your typical farm crop. Mushroom cultivation doesn’t require tractors, acreage or sunny days. However, like all other crops, mushroom cultivation requires the proper substrate; appropriate environmental conditions; the reduction of disease and pest pressures; and proper harvesting, handling and storage. Whether inside in a controlled environment or outside in a forested production area, growing mushrooms is becoming a respectable farming niche.
A colorful variety of mushrooms.
Photos courtesy of Wiltbank Fa rms unless otherswise noted.
As a primary crop for small growers or a high-value niche crop for diverse enterprises, the popularity of edible mushroom cultivation is on the rise. Although large-scale mushroom growers dominate the production of the Agaricus mushroom species (like white buttons, portobellos and cremini), specialty varieties that don’t belong to the Agaricus genus, such as shiitake and oysters, are cultivated on a much smaller scale.
According to the National Agricultural Statistics Service, there were over 200 growers of specialty mushrooms in 2010, and 112 growers of Agaricus species. The Agaricus growers tend to be larger operations that supply the wholesale markets, many of which are centered in Chester County, Pa. During the 2009-2011 period, sales of specialty mushrooms grown in the U.S. increased by over $10 million, indicating an increasing demand and a growing market.
Dan Burden, of the Agricultural Marketing Resource Center at Iowa State University, advises growers interested in mushrooms to start small.
A bounty of yellow oyster mushrooms.
“There are many sources of hobby and small-scale production mushroom farming kits and supplies on the market. These are a great way to get into mushroom culture and gain the basic know-how prior to considering mushroom production as a business venture,” Burden said. “In supporting many start-up businesses of this type, I stress getting in with minimal capital outlay [overhead and risk] until a person can figure out if the production system can be made to turn a profit, develop markets for the product, and pretty much figure out if the venture is right for them.”
Candice Heydon, of Oyster Creek Mushroom Co. in Maine, grows shiitake and oyster varieties year-round, and distributes wild-foraged black trumpets, morels, porcini, chanterelles and more. Not all edible mushrooms are adaptable to cultivation, and many specialty mushrooms are wild-foraged. These wild-foraged mushrooms supplement the 2,000 pounds per year she grows for fresh, dried, powdered and other value-added sales. Heydon works with over 100 pickers, as well as some small growers who sell what they cultivate back to Oyster Creek. She also sells do-it-yourself mushroom growing kits for the hobby grower.
Heydon once grew twice the amount of mushrooms she now does – not for lack of demand, but rather due to the time and labor requirements. After 25 years in the business, she reports that demand for high-quality product remains strong. In fact, many of her mushrooms are sold prior to harvest.
Shiitake fruiting from sawdust substrate.
While Heydon distributes value-added mushroom products across the nation, she also sells fresh mushrooms regionally, and has a home kitchen license as well as a mobile vending license, so she can make and take mushroom products, such as pâté and flavored oils, to several area farmers’ markets. She also sells to restaurants and health food co-ops. Her website (www.oystercreekmushroom.com) generates a portion of her sales, particularly for the growing kits.
Gary Wiltbank grows shiitake and oyster varieties of mushrooms in Saugerties, N.Y. He also sells to restaurants and health food stores, with any remainder direct-marketed via farmers’ markets. Wiltbank has been growing commercially for a decade and knows who his customers are.
“People who do like mushrooms are a consistent and loyal following,” Wiltbank said. “You have to understand your customer base.” Wiltbank estimates that about 9 percent of customers who shop at farmers’ markets will purchase specialty mushrooms, so the consumer pool isn’t large. Even many chefs, Wiltbank said, are not familiar with using specialty mushrooms, but the ones who want them tend to seek him out and become regular customers. As a result, he is “almost contract growing” for many restaurants, with many standing orders each week.
While mushroom growing may seem simple, doing so successfully is challenging, time and labor-intensive, and very much dependent on precise environmental parameters.
The traditional way to grow mushrooms is outside in logs, preferably oak. Heydon uses this approach and currently harvests from 300 logs each year, with a yield of about 300 pounds of mushrooms. The green, fresh logs are cut to size (3 to 4-foot lengths) and a hole is drilled where the spawn will be inoculated. In order to keep as sterile an environment as possible, the end of the log must not touch the ground. Any damage to the bark will damage the fungi crop, and as there are natural mycelia competing to colonize the wood, a grower cannot use just any old wood.
“The log is already sterile. It has an immune system,” Heydon said of newly cut wood, which must rest a few weeks or more before inoculation.
Spawn is any substrate that contains mycelium, or the vegetative part of a fungus. The mycelium grows and eventually fruits. The fruiting body is the mushroom itself. Mushrooms produce spores, not seeds, which then germinate and form mycelium after some complicated steps. Mycelium has to “hunt for food,” Heydon explained, feeding on organic matter. It decomposes the wood or other growing substrate for nutrients. Logs cut in winter have a higher sugar concentration (which promotes mycelium growth) and are preferred.
Heydon uses purchased plugs containing small bits of mycelium. Once placed into the drilled holes and sealed with wax, the mycelia will grow and colonize the log. Logs are stored in a shady area protected from wind, and the mushroom harvest will be ready naturally in about a year. The logs need to retain enough moisture to keep the mycelia alive, so the appropriate forested area is needed for optimal production.
To speed things up, the mycelia can be stressed into fruiting by exposing them to large quantities of water, Heydon said. Soaking the logs in a tub of water will force fruiting. Each log can be forced several times before the decomposition is too extensive. During her peak production years, Heydon was soaking up to 200 logs each week in large tanks.
Slugs are the major pest issue with outdoor production, Heydon noted. She has found that baiting with beer and handpicking the slugs are the best control methods.
Winter weather in the North is not conducive to mushroom fruiting, so outdoor fruiting in cold climates is a spring to fall enterprise. Growers who want year-round production must move indoors to a controlled climate, akin to greenhouse vegetable growers. Indoor growing also provides more control over environmental factors and results in more regular and faster cropping schedules, with a much quicker crop rotation cycle and increased yields over outdoor systems. Indoor production of shiitake and oyster mushrooms is successful year-round with appropriate environmental controls.
Oyster Creek Mushroom Co. at the farmers’ market.
Photo courtesy of Oyster Creek Mushroom Co.
While logs can be used indoors, many growers use other substrates, such as straw or sawdust blocks. Heydon has a 120-square-foot greenhouse, very low-tech, for winter production. She grows on 8-pound blocks, which will each produce about 6 pounds of mushrooms. The crop cycle is measured in days rather than months, with a new crop ready every seven days.
Fungus fly, which Heydon compares to the blueberry maggot, is the main pest concern indoors. She controls access to the greenhouse to prevent contamination of the blocks, and hoses down the room between crops. Air exchange is important, and her ventilation system runs four times per hour. Light, temperature and humidity must also be closely controlled to provide the optimal growing conditions.
“If the environment isn’t right, you’ll know it right off,” Heydon said. Mushrooms that have leggy stems and small caps are the result of less-than-ideal conditions.
Oyster mushrooms growing on straw-filled plastic tubes.
Wiltbank grows indoors in a 20-by-60-foot heated space, as well as in an unheated 20-by-30-foot space, which is in production about nine months of the year. His cement block building is insulated and lined with plastic, which can be hosed down with a bleach solution to sanitize between crops. The mushrooms produced in the unheated room are a nicer product, according to Wiltbank, because of the environmental factors.
“The closer you can keep this thing to nature, the better off you are,” he said.
Wiltbank uses his own or locally grown wheat or barley straw for production of oyster mushrooms. The straw is pasteurized in a 300-gallon stainless steel tank. After soaking, steaming and a period of cooling, the straw is inoculated with a liquid grain spawn, which he makes himself.
Once the spawn is inoculated into the straw, it is packed into plastic tubing that measures 12 inches in diameter and is perforated. This simulates a tree trunk. The mycelium will fruit out of the holes as it grows. The substrate, which is only viable for one-time use, is used as compost by local gardeners or spread in Wiltbank’s hay fields.
Because shiitake mushrooms are slow colonizers and need more time to incubate, Wiltbank opts for sterilized sawdust pre-starts, which he buys from a commercial grower in Pennsylvania. The shiitake is grown in sawdust, and the substrate can fruit two to three times, with a seven-day period between crops, before disposal as compost.
Controlling the environment
According to Wiltbank, it is possible to overcome the stressors of indoor growing environments “if you have strong, vibrant spawn and your environmentals are even close.” However, getting those environmental factors right takes a lot of effort.
“Some varieties are more sensitive [to temperature],” Wiltbank said. He is careful to monitor conditions throughout the growing room, and he knows that some mushrooms are better off near the fan, or situated in other microclimates that develop. His yellow and pink oyster mushrooms are native to warmer climates, for example, while the blue and brown oysters are not. Temperature in the room must be kept between 60 and 70 degrees Fahrenheit.
Constant airflow is critical, Wiltbank said. He does not find it cost-efficient to filter the air, but has exhaust fans on timers to keep the air exchange going. Mushrooms produce carbon dioxide, and removing excess from the room is crucial. The humidity needs to be monitored and kept at 80 percent or better, and the outdoor temperature and conditions have an impact on humidity regulation, which must be monitored constantly.
“There is less moisture in a cubic foot of air at 20 degrees than at 80 degrees,” he said. As the seasons change, the climate in the growing facility needs to be adjusted. “The more hands-on a person is, the better off you are,” added Wiltbank.
The crops are harvested with a two to four-week turnover, depending on the variety, Wiltbank said. Because the crop is ready for harvest so quickly, he is able to respond to market demand, and can decrease or increase production accordingly.
What can’t be altered is the time of harvest.
“When they are ready, you pick them,” he said. “There is no holding until the morning.”
Shiitakes grown on sawdust substrate.
It is better to hold postharvest rather than delay the harvest, he explained. The mushrooms are handpicked and stored in a walk-in cooler, which is critical to the operation. They are sold, at most, within three days of harvest. The shelf life once they reach the customer depends on storage conditions being kept consistently cold, but typically his mushrooms can last for at least a week. Shiitakes are better keepers than the oysters.
“You better have an outlet,” Wiltbank said. With up to 350 pounds being harvested per week, Wiltbank’s regular customer base is crucial. His customers tend to be discriminating, conscious of quality and knowledgeable – and they understand value versus price.
Farming for a living
“This is a viable way to sustain a family farm,” Wiltbank said. “It’s labor-intensive. You live the whole deal. It’s not a part-time job. It does consume you.”
Currently, Wiltbank is seeking a partner who can help to better utilize his growing space and equipment.
“A partner ideally would blend into my current operation and also utilize my current acreage and greenhouse to expand a product line of high-end produce,” he said. “You cannot do everything yourself.”
“Any small-scale venture is viable if it provides ample return on investment for the commitment the grower puts into it,” Burden said. For those interested in starting a mushroom operation, Burden recommends that specialty mushrooms be tried on a small scale without much up-front investment before a greater commitment is made. While large-scale growers tend to concentrate on Agaricus mushrooms, other edible types are a viable option for smaller operations.
“It’s a small production, niche operation,” Wiltbank said of his mushroom farm. “It’s a good fit for me.”
The author is a freelance contributor based in New Jersey. Comment or question? Visit