Benefits of Growing Mushrooms on a Log

Growing mushrooms on a log may very well be the oldest form of mushroom cultivation. After all, it wouldn’t take much for a stone age person to bring home a log that was producing tasty mushrooms. More recently, the Japanese have been growing shiitake mushrooms on logs for hundreds of years, longer than we have been growing button mushrooms on pasteurized, composted steer manure. Their method was actually quite simple. Put fresh logs next to fruiting logs. When the log produces mushrooms, if it makes the right kind, you keep it. If not, you don’t. When it comes time to coax it to produce mushrooms, you soak it for a day in a lake and then smack it with a wooden mallet. I am not sure what the mallet is supposed to do, though.

Many of the best gourmet and medicinal mushrooms are primary decomposers. This means that they prefer to grow on fresh wood. Many mushrooms growers today will chip the wood and grow the mycelium on wood chips. This increases permeability and surface area, thus increasing the speed that mycelium can colonize the wood, thus increasing the speed of mushroom production. However, for the home grower, growing on wood chips can mean more potential for problems and more maintenance. Obviously, a greater surface area also increases potential opportunities for contamination. Also, wood chip blocks must be fruited on a more regular basis and are used up more quickly. A mushroom log will last for several years and requires less maintenance than a house plant.

Actually making a mushroom log is relatively easy. There are many methods for making a log and I will highlight two of those in an upcoming post. However, the first step is pairing the right mushroom with the right kind of wood. Some mushrooms tend to be pretty specific about what kind of wood they prefer. Here are a few likely candidates and the woods they prefer:

Lentinula edodes (Shiitake Mushrooms)
Shiitake is probably the most common commercially available mushroom log out there. It is also one of the more commonly available gourmet mushrooms out there. It is easy to grow. As for logs, it actually prefers shii trees. In fact, that is what it is named after. Shii is the tree and take (pronounced tak-ay) means mushroom in Japanese. However, we don’t have many shii trees here, so oaks do nicely. It will, however, grow on a number of other hardwoods, such as poplar, willow, cottonwood, and birch, among others.

Pleurotus ostreatus (Pearl Oyster Mushrooms)
Oyster mushrooms are another ubiquitous favorite of the gourmet mushroom aisle at your specialty store. They also happen to be one of the most aggressive and easy to grow mushrooms. They will grow on most kinds of hardwoods and adept at turning the mass of the log into a serious mass of mushrooms. However, they also have a problem. Oyster mushrooms put out a LOT of spores. So if you are prone to mold spore allergies, this may not be the mushroom for you. It is perhaps worth noting that my wife is prone to these allergies and it doesn’t seem to bother her, though. Nonetheless, I tend to do my best to keep the fruiting bodies out of her way and pick the mushrooms as young as I reasonably can. Also, there is a closely related species called Pleurotus pulmonarius that favors conifers, especially fir and spruce.

Hypsizygus ulmarius (Elm Oyster or Garden Oyster Mushrooms)
This one is a good substitute for Pearl Oyster Mushrooms. It is very close in flavor and appearance to Pearl Oyster mushrooms, though some say the Elm Oyster is tastier. However, it is not as aggressive, and it produces far fewer spores. Elm Oyster Mushrooms prefer elms (of course), but also like cottonwoods, maples, oaks, and willows.

Hericium erinaceus (Lion’s Mane Mushroom or Pom Pom Mushroom)
All of the mushrooms above are very mild in flavor. I included Lion’s Mane Mushrooms on this list because they are not. They have a very strong flavor. Some say they taste like lobster. I disagree. They also have a very interesting form. They do not have a cap or a stem or gills. They are more like a fuzzy ball. Well, maybe not fuzzy, as the protrusions coming off the mushrooms are not like hairs at all, but more like teeth. Pom Pom is a good description. They like to grow on oak, maple and walnut. Hericium abietis (Conifer Coral Mushrooms) are a good substitute if you have spruce logs to grow on, though it forms more of a coral shape than a ball.

Ganoderma lucidium (Reishi Mushrooms)
Reishi Mushrooms are not edible mushrooms. It would be like chewing on wood. They, are, however, prized medicinal mushrooms. They are full of antioxidants and are renowned for boosting the immune system. Reishi mushrooms also have a beautiful dark red color on top and creamy color on bottom that bruises a darker color when fresh. I carved my daughter's name in one and she loves it as a name plate. Reishi mushrooms love to grow on most varieties of broad-leaf hardwoods.

Trametes versicolor (Turkey Tail Mushrooms)
Turkey tails are another medicinal mushrooms. While they provide some of the same benefits as Reishi Mushrooms, they are particularly renowned for their cancer fighting properties. They are also lovely, growing in a shelf like shape with multi-colored stripes. The advantage of Turkey Tail Mushrooms is that they will grow on just about anything but cedar and redwood.

There is one last thing to remember about log selection: the size of the log. Your log should be between 4" and 12" in diameter. If you get too much bigger, it will take a really long time for the log to produce mushrooms. The fungus won't go about producing fruit until it has colonized the whole log. If the log is too small, it will produce relatively few mushrooms. Length is another consideration, and that has a lot to do with where you are storing the logs. If you live in a humid, relatively rainy area, you can store them on the north side of a building, out of direct sunlight and let nature do most of the work. For that, logs 4-5' long work well. If, like me, you live in a dry climate where the mushrooms will need additional help retaining moisture, keeping the mushroom in a pot is a good alternative. You can then fill the rest of the pot with sawdust (more food for the fungus) or just potting soil and water it like a plant. If you do that, a log that is 2-3' long would work best, depending on your pot and your space. If you try to make it much longer, it tends to get top heavy. Also, the pot only really retains moisture for the area it covers and maybe 6" higher. The tops of tall logs will still dry out. If you get much shorter than 12" or so, you start to reduce your potential harvest.

Coming up: How to make a mushroom log.