Growing Shiitake Mushrooms on a Log
Using a Mushroom Log to Grow Shiitake Mushrooms
By Anita B. Stone, North Carolina – If you ever wanted to grow mushrooms on the homestead and make a decent wage, growing shiitake mushrooms is the way to go. This tasty fungus not only offers great health benefits, but can bring in tasty cash benefits—and more. Shiitake is the Japanese name for a type of mushroom that grows in the shape of a flattened umbrella on wood. The taste has been compared to an exotic blend of filet mignon and lobster, with a hint of wild herbs and a tad of garlic.
With as few as two acres and a good mushroom growing guide, you have the ability to grow more than 500 pounds of shiitake on one cord of wood. Once grown, you are on the way to increasing your income on the homestead.
When growing shiitake mushrooms under controlled conditions indoors, the mushrooms can be harvested in as little as three to four months. Instead of using natural logs, a special growing medium made of oak sawdust and rice hulls is used. This is first sterilized and then inoculated with a special strain of shiitake. Inoculation takes place in a sterile chamber made from a recycled fish tank equipped with ultraviolet light. This ensures that each mushroom is identical. The inoculated container is then sealed with plastic, which allows air exchange, but not contamination. Each area is labeled, dated and stacked on shelves in ordinary subdued room light. After three months, what appears to be a log is actually composed of thin strands of shiitake mycelia. (Mycelia are the part of the body of a fungus, which grows inside another mass.) The whole log is placed in a plastic box, watered, misted frequently with water, and kept at 70°F. Mature bud formation takes several weeks until the shiitake pops out.
When growing shiitake mushrooms outdoors, it normally takes up to two years for a harvest to enhance the landscape, but requires much less work. To grow on hardwood, evergreen, or oak wood, small holes are drilled in each log. Wood chips (or dowels) are inoculated with shiitake mycelium then pushed into the pre-drilled holes, and immediately covered with hot wax to prevent contamination. The number of holes depends on the wood and how far apart you decide to plant, but normally 10 to 20. Logs can be stacked or left singly in the lot raised off the ground so they aren’t contaminated with other mushroom spores.
The beauty of growing shiitake mushrooms outside is that after felling the trees and inoculating the logs, there is no additional labor, except for the harvest during spring and early fall. The mushrooms will not survive on living wood, so there is no danger of harming a wooded lot. Logs are stacked and watered to maintain an optimal log moisture content of 35-45 percent*, and often covered during severe weather to protect the harvest. But, left on their own, they will still produce a profitable crop.
“Growing shiitake mushrooms is a great investment for farming,“ David Spain of Spain Farm in North Carolina offers. “There are not a lot of mushroom farmers on the homestead yet, so it is a wide open area for a good cash crop.” Spain began outdoor mushroom production in 2006 with shiitake. “We currently sell the crop at three different farmers markets. We also sell to restaurants throughout the Piedmont.” Spain wants to begin experimenting with three other strains: Maitake or Hen of the Woods, Lion’s Mane and Pearl Oyster. “The whole family becomes involved. We kind of taught ourselves, and used common farm equipment to get started—a regular drill and an angle grinder, which assists with more than 10,000 rpms, and sped up the process. We just learned as we went along. We now use four-foot oak or sweet gum logs. And there is practically no debt involved.” The first year Spain experimented with 200 logs, the second year with 500 logs, “and now we’re producing mushrooms on 2,500 logs,” he announced.
Spain has worked out an economically and sustainable agreement with a tree farmer. “When his forest needs to be thinned, I can get my logs from him. The drill, the bits, 100-pound boxes of wax and $25 for inoculators is about the typical prices these days.”
As for a mushroom orchard, the possibilities are unlimited. States that offer both the right climate and soil, are many. Currently, there are 75 small mushroom orchards in North Carolina. “This crop could revitalize the farming industry,” Spain offers. “A 15-acre crop takes three to five years to produce. Hazelnut logs produce in about four to five years, the hardwood oak takes 10-12 years.” The fungus is well on the way to becoming a quality cash crop.
Growing shiitake mushrooms makes a great family project for anyone interested in homesteading today. Spain shared his expertise in creating a mushroom farm orchard. Materials required consist of one freshly cut log, a shiitake spawn or sawdust, a hand drill, a paintbrush, a rubber-head mallet, organic beeswax, and a heat source and a saucepan (for melting the wax).
Spain recommends using freshly cut logs, preferably cut in the last 72 hours with a 150mm diameter and no less than 75cm long. Once the wood has been selected, drill each log with about 20 holes, evenly spaced in a zig-zag pattern around the log. The width of the holes should be 8.5mm if you are using a standard plug spawn. The diameter of the plugs increases from swelling in the damp spawn environment. If you decide to use a sawdust spawn, drill 12mm holes. The next step is to fill the holes in the log with shiitake spawn, which can be ordered online. Spawn can be of the dowel-type or sawdust. Hardwood dowels or sawdust plugs are infused (inoculated) with a specific mushroom species, in this case, shiitake.
To inoculate the log, take a spawn plug and tap it into the hole. Repeat this procedure until you fill all the holes. Seal each hole by sealing it with melted beeswax. Here’s how to successfully melt beeswax. This ensures that each open surface will be protected from other fungi that may be eyeing the holes for their existence. Because the mushrooms will absorb whatever they come in contact with, it is preferable not to use artificial-based waxes or sealants on the food. Just simply seal any openings in the log as well as each end and each hole with melted beeswax, organic when possible.
Once the log is prepared, place it somewhere with good airflow, preferably in semi-shade. Make sure it’s not on the ground. Some growers place their logs up in tree branches to keep it safe and moist. In six to 12 months you will begin to see shiitake sprouting up from the holes in the logs. The logs should yield quality harvests the first time. The potential for growing shiitake mushrooms is favorable and the extra income adds to the plus side of the financial balance sheet for any homestead.
For more instructions on growing shiitake mushrooms, visit www.centerforagroforestry.org/pubs/mushguide.pdf
Originally published in the November/December 2013 issue of Countryside & Small Stock Journal and regularly vetted for accuracy.