The growing market for shiitake mushrooms

Photos by John Hibma.
A log nicely fruiting with shiitake mushrooms.

Jim Peppin, along with his partner, Carol Brzozowy, has been raising shiitake mushrooms at their Maggie’s Farm location, in Lebanon, Conn., since 2002. The farm got its name from the lyrics of a Bob Dylan tune.

Shiitake mushrooms (pronounced shee-tah-key) are a darker and stronger flavored cousin of the common button mushroom. They originated in the Orient centuries ago, and today, there are literally millions of pounds produced there each year. They’ve been gaining in popularity in the United States for the last few decades. Not only is the shiitake a popular gourmet mushroom, it’s widely regarded for its medicinal value, as well.

Jim Peppin shows how the cap is pulling away from the stem of a shiitake, just a day away from picking.

According to research from Penn State, worldwide mushroom production has increased more than 20-fold in a 30-year period. While the common button variety is still the most popular, the shiitake is coming on strong. The shiitake is also the best studied medicinal mushroom and is well documented to have both antiviral and antibacterial properties. The shiitake mushroom is hearty and can be refrigerated for weeks. If it dries out, it can be quickly rehydrated by soaking in water for a couple of minutes. They also can be frozen for later use.

Peppin, who’s a prolific gardener, started raising shiitakes mostly as an experiment. With the help of a local friend, he researched growing the mushroom, decided to give it a try and harvested his first crop in the summer of 2003. He has a minimal investment in the project, but growing shiitakes is almost as much an art as it is a science—mushrooms can be fussy little plants with growing conditions having to be just right in order to raise them on a consistent basis.

From the earliest times, the shiitakes were found to grow quite well on certain varieties of hardwood logs. The Chinese found that if you cut a log that had a shiitake growing on it and soaked it in water it would bear more fruit, and the process could be repeated numerous times as long as the log remained free of other molds and had not begun to decay. That was the beginning of the commercial growing of shiitakes.

Today, Peppin follows the same growing method and routine as the early Chinese, using natural hardwood. He works primarily with logs from oak trees. The logs must be of a specific size and diameter, about 40 inches long and 3 to 4 inches in diameter. He works with local tree cutters who can supply him with just the right size log. The logs have to be handled fairly carefully so the bark has not been disturbed. “Some of my suppliers didn’t understand that when I first started working with them,” he said. “They thought you could just find any old oak tree that might be sick or diseased, cut up the branches to the 40-inch length, toss them into a truck and bring them to me.”

If logs are in any way damaged with a piece of bark torn or missing, the bare wood provides an entry point for other fungi and contaminants that will prevent the shiitakes from growing. The shiitake mushroom needs a sterile environment on a very healthy log.

In order to get mushrooms to grow on the logs, they have to be inoculated with a spawn. Spawn is essentially the mushroom seed, and most spawn for mushroom growers is commercially prepared by way of cultures. Peppin purchases his spawn from a supplier.

A 3/8-inch-diameter hole is drilled 1 inch deep into the log with a special drill bit and the spawn is inserted in the hole with a special plunger tool. Holes are drilled about 6 inches apart down the length of the log and then around the circumference of the log in a diamond shape pattern, leaving holes about 3 inches apart as they encircle the log. Peppin inoculates heavily, thereby improving the chances of getting a good fruiting on his logs. Once the spawn is inserted, the hole is covered over with wax. Peppin has been using cheese wax for this purpose. Sealing the hole prevents the spawn from drying out.

Jim Peppin at the Coventry Market last summer.

Peppin inoculates his logs starting in February and continues through April. It then takes nearly a year for the first mushrooms to appear on the log. During that year, spidery threads called mycelium grow from the spawn and spread through the entire log. This growth process is timed so that the mushrooms will appear in the spring and summer of the following year—just in time for the fresh produce marketing season in Connecticut. Once a log has been inoculated with spawn it will continue to fruit in the spring and summer as long as the logs are kept moist and free from damage.

Mushrooms need a cool, moist and temperate climate to grow so it’s imperative that the logs are kept moist as the mycelium grows in the log. Peppin watches his logs closely and makes the decision to soak the logs based on the experience he’s gained in the years he’s been growing the shiitakes. When the following spring draws near, the mycelium, which is a white powdery substance, will often appear at the butt ends of the logs and he immerses the logs in a tub of water for two days. As a general rule, when the logs are removed from the tubs, the mushrooms can begin popping through the bark in just a couple of days. Peppin props the logs up vertically against a low fence and as the mushrooms grow, the stems will turn upward after the buttons have emerged and the mushroom will grow into an upright position on the side of the log. The proper time to pick the mushrooms is after the cup breaks away from the stem.

Peppin raises three strains of the shiitake: a wide range strain, a cool strain and a warm strain. Each strain responds differently to the weather, so by having the three strains he can be confident he’ll get a good supply of mushrooms no matter what the Connecticut weather might be during the summer. How much a log will fruit is dependent upon the climate, but he estimates that each of his 40-inch logs will produce an average of 1 pound of mushrooms at each fruiting. Sometimes, he’ll have a log that fruits heavily and he may harvest 2 pounds of mushrooms. “After a ‘spawn run’, the logs are set aside from four to six weeks,” he explains. “Then, they’re stimulated with another submerging in the tub, and within 24 hours the tiny pinheads will appear and a day or so later new mushrooms can be picked. They grow that quickly.”

This past season, which ran from May through October, Peppin and Brzozowy retailed their shiitakes, along with their other garden produce, every Sunday at the Coventry Regional Farmers’ Market. This is their fourth year participating at that market. Peppin estimates that he sold an average of 10 pounds of mushrooms per week through the season. He charged $16 a pound this year and sold out each week, which proves the popularity of the shiitake.

By the end of October, the markets are winding down and the mushroom production has slowed down. Peppin then stacks the logs away for the winter months in a shaded, protected spot on the farm, being careful not to damage them. A few logs will continue to produce a few mushrooms even during the winter, and Peppin and Brzozowy will keep them for home use.

Good, healthy logs can be productive up to six years. Now that Peppin is into his fourth year he’s starting to see some of his first logs becoming less productive. All the while, though, he’s been steadily increasing his crop with more logs each year. For Peppin, the process of growing shiitake mushrooms is still a learning experience, but definitely an enjoyable one that contributes some extra income during the summer.

The author is a dairy nutritional consultant and works for Central Connecticut Farmer’s Cooperative in Manchester, Conn. He can be reached at Hibmajl@cox.net.