The article on growing mushrooms on hardwood logs in the Spring 2009 edition of Northern Woodlands intrigued me. My 16-acre woodlot in North Wolcott, Vermont, had been cut-over hard in the early 1990s. Since then, I’ve been managing it for a small, 200-tap sugaring operation, which may grow to 300 taps as the trees mature. When the article suggested using small-diameter hardwood logs for producing mushrooms, I imagined that the small trees I thinned every year to enhance the crowns of my maples could be used to grow mushrooms.
That spring, I ordered mushroom spawn from Field and Forest Products in Peshtigo, Wisconsin, mainly because owners Joe and Mary Ellen Krawczyk talked with me on the phone about my plans and made suggestions for my northern Vermont location. I devoured their inspiring catalogue and settled on the idea of growing shiitake mushrooms. The shiitake grabbed me because of its high protein content and its reputation for nutritional value. Chefs consider it a delicacy.
High-density hardwood species are said to be ideal for growing shiitakes, with oak rated the best. No oaks grow on my woodlot, so we tried sugar maple, beech, and yellow birch. Fruiting occurred on all three species, but sugar maple was by far the best of these three for quality and quantity, at least in my location.
I used a “wide-range” strain of sawdust spawn called WR46, as it was recommended as the most appropriate for beginners. This spring, as I expand, I plan to try a cold-weather strain (ideal for spring and fall fruiting) and a warm-weather strain (intended for hot mid-summer conditions). Within each strain are mini varieties like West Wind, Double Jewel, and Native Harvest. Each variety of spawn is said to complement a particular log species. My next order will be for Double Jewel, because Joe thinks it might be good for growing on yellow birch. New Moon is a new strain that he thinks might work well with red maple.
The type of spawn is another decision. I went with sawdust spawn because, although it requires a more demanding inoculation procedure, it’s less expensive than thimble spawn or plug spawn. I tried two methods of inoculation and wound up preferring the kerf method, where you take the point of your chainsaw and make cuts about one inch deep on each side of each log. After the spawn is rubbed into the cut, candle or canning wax is melted and painted over each inoculation site to make sure the spawn doesn’t dry out prematurely. I made an inoculation festival out of it with friends, building a campfire in the woods with a grate to melt the wax in a large, clean vegetable can. We felt like alchemists practicing a new kind of alchemy.
Placement of the logs after inoculation was tricky, as I needed both shade and access to water. I tried two locations near a beaver pond in my balsam woods and placed the rest of the logs on the north side of my sugarhouse. Big operations use water tanks and heavy equipment to keep logs moist in dry spells and to force fruiting. Not having that option and starting out small, I had to be creative – leaving the logs flat on the ground in hot, dry periods, and propping them up when rain came. By the end of the first summer, it was clear that the north side of the sugarhouse location was the best. I moved all 50 of my four foot logs (3 to 8 inches in diameter) there and was blessed with an immediate fruiting. It was as if the logs liked being together, benefiting as they all did from concentrated watering from the sugarhouse roof.
The biggest challenge was slug removal. Remembering an old garden trick, I put down saucers of cheap beer, which the slugs seemed to prefer to the spawn. Still, I had to inspect the logs frequently, especially in wet periods, and remove by hand the slugs that missed the beer. Next year, I may try a trendier beer to see if the slugs might find it more to their liking.
Five pounds of spawn was sufficient for 50 logs, at least using the kerf method of inoculation. I found this produced enough mushrooms for our own use and to share some with friends. The logs will fruit, depending on conditions, for two to eight years, so we’re set for a while. I plan on inoculating 50 to 100 logs each year, a number that will work without over-cutting my small woodlot. I can now visualize sales at local farmer’s markets, alongside my syrup crop.