Growing Mushrooms on Logs

For those who love mushrooms, there’s nothing like eating and cooking with ones that have been freshly picked. So, why not grow your own! Wood mushrooms like oyster, and shiitake can be grown on logs, are chock-full of nutrients, and are easier to grow than earth mushrooms like morels or chanterelles. If you have a shady garden area where nothing grows well, this is the perfect place to start a mushroom log garden! This article will go over the steps for growing mushrooms on logs.

Sourcing the Mushroom Spawn

First and foremost, you will have to source out mycelium for your mushrooms to grow. A quick search will bring up various online options that will sell plug spawn, sawdust spawn, and grain spawn. Any of these will work, but this article will focus on plug spawn, since they are the simplest to use for beginners. There are many varieties of shiitake and oyster plug spawn to choose from, and even tools and special kits to purchase. Otherwise, all you really need is a drill, drill bit, and wax.

Wood Size and Specifications

Mushrooms will grow on large pieces of wood, but ideally the logs should be 4-6 inches round on 4-foot lengths. This size will be easy to handle, and is also an ideal sapwood-to-size ratio for quick and efficient colonization. Use freshly cut pieces, or ones that have fallen from a healthy tree from a recent storm, as they are less likely to have been inhabited by competing fungi.

Ideally, bark will be fully in tact for protection and moisture-retention, as well. Cutting logs in the winter will help prevent bark from shedding off, but early spring is also a good time to cut, as long as it’s before any tree budding. Keep the logs moist and away from sun and wind exposure. If you have a woodlot, you should be able to find something suitable, otherwise contact local tree cutting services, or check out online community sites for people selling or possibly just getting rid of tree cuts.

Best Wood Types

Hardwoods like oak, beech, birch, ironwood, western adler, and hickory are some of the best varieties to use for shiitake mushrooms because of their long production life. Soft hardwoods like maple, aspen, and poplar are better for growing oyster mushrooms. Do not use evergreen logs, or wood from fruit trees. Ash, elm, and, walnut are not recommended, either.

Prepping the Space

You want to either mimic or already live somewhere with forest like characteristics. Consider utilizing space under a large tree; mottled sun is fine, but mushrooms need damp, shaded areas to thrive. Clean logs with a scrub or wire brush, and make sure they have at least 35% moisture content before inoculation.

Inoculation Time!

The best time to inoculate is early spring. Measure the length and width of your plugs and choose a drill bit width that will allow them to fit snugly inside the holes. Drill just slightly deeper than the plug length so that when they are hammered in, they are slightly recessed. Use tape on the bit to know where to stop drilling. Start with one row and drill a hole every 3-4 inches, staggering the next row to create a diamond pattern over the whole log. Some people like to put more holes around knots and stems to speed up inoculation. Cover all of the plugged holes with melted wax - beeswax or cheese wax is preferred, though some use paraffin. An old pot can be used to melt the wax, and a small paint brush to apply, making sure to cover the branch ends as well so that no competing fungi can enter the wood. Label your logs!

Incubation Period

Once the logs are inoculated, keep them stacked low to the ground to keep moisture in. Soaking may be necessary if you live in dry areas with little or no snow. It takes 4-6 months for the mycelium to colonize the log, generally summer and fall, before they go dormant through the winter. When the thaw starts, move them into criss-cross patterns to allow for more air-flow and easy harvesting. Once spring arrives and the rain starts, you should see mushrooms starting to grow! Incubation times will vary between six months to sometimes two years based on the type of spawn used, mushroom variety, and climate conditions, but generally speaking you should be able to harvest within a year. Oyster varieties grow faster than shiitake.

Forced Harvesting

Rather than waiting for spring, some people will force fruiting in a couple different ways. You’ll know a log is colonized when enough time has passed, and you see the mycelium (white, thread-like species) emerging from the bark or at the cut ends of the log. Soak the log in cold water for a few hours up to a week to get oyster or shiitake to fruit. Shiitake will also respond to stomping, but only if it has been fully colonized and is ready for a physical shock.

Growing mushrooms on logs is a great way to add high-quality, nutritious produce to your diet. For many, it's a labor of love, and a small price to pay for years of fresh harvests. You don’t have to be a mycologist to grow high-quality mushrooms: you just need to follow a few simple rules, and have some patience.