If you have a little bit of land or even a small yard, you can grow your own gourmet culinary and medicinal mushrooms outside for years to come. Mushroom log cultivation is a style of farming that dates back about 2,000 years and is still a great low-tech way to grow mushrooms today.
This method of mushroom cultivation mimics how mushrooms thrive in the wild. Hardwood dowels laced with mushroom mycelium are plugged into freshly-cut logs or stumps to inoculate them. The mycelium will start producing fruiting bodies after a full year of growing and can go on to produce every year for five years or even longer, depending on how long the log takes to fully decompose.
Growing mushroom logs is a bit of a waiting game. Unlike indoor mushroom grow kits that produce fruiting bodies almost immediately, you’ll have to wait nine months to a year for mushroom logs to produce. The payoff is that you’ll get seasonal crops for years to come! There’s no more exciting and rewarding way to grow mushrooms.
Using mushroom plugs is fairly simple but does require a few tools and little bit of understanding of how mushrooms grow. Below, we’ll teach you how to use mushroom plugs and get your own backyard mushroom farm going!
When to start mushroom plugs
The best time of year to inoculate logs with mushroom plugs is in the late winter, when your logs have higher concentrations of sugar. Some species are more delicate than others and need to be inoculated after the last frost date in your local area. (Our mushroom plug species can generally be started before last frost, unless you live in an area that consistently experiences hard freezes for extended periods.)
Great mushroom species to start with are Oyster mushrooms and Shiitake. Oysters will produce mushrooms from spring to fall. They have a shorter incubation period, so if you plant them in late winter, they could start fruiting the fall of that same year. Shiitake has a longer incubation period and may take nine months to two years before they produce mushroom bodies.
How to choose logs for inoculation
When planting mushroom plug spawn, it’s important that you use the right logs. Mushrooms in the wild grow on dead trees, working to decompose organic matter in order to acquire the nutrients they need to flourish. Each species has its own tree preferences, so your first step is to find the right kind of wood. Oyster and Shiitake mushrooms both prefer hardwood tree species such as alder, birch, oak, maple, cottonwood and beech.
The next thing to consider is the health of the tree. Trees that are already decaying have other species of fungi growing in them, meaning more competition for your mushroom spawn. You want to select fresh, healthy trees for your mushroom logs.
Harvest your tree(s) during the fall or winter, when their leaves have fallen and their sugar concentration is highest. Once they’ve been cut down, the logs should be inoculated as soon as possible – no later than a month or two after. The longer they’ve been down, the more opportunity for other mushroom species to populate them.
The logs should be four to ten inches in diameter and two to five feet long. Stumps of hardwood trees can also be inoculated if you cut a ring in the bark at the soil level and the stumps are two to four feet tall.
Setting up your mushroom logs does require a few tools. Here’s what you’ll need to collect:
- A hand drill and a 5/16th inch drill bit
- A wooden or rubber mallet (a standard hammer will work, too)
- Sealing wax
- Something to melt your wax with, like a crockpot or old pan (a clean, empty tin can will also work)
- A one-inch bristle paint brush.
Inoculating logs in 5 steps
Once you’ve gathered your tools and you’ve got some fresh logs ready, it’s time to inoculate! This is what you need to do:
1. Drill your holes
Use your 5/16″ bit, set to approximately one inch depth using a bit stop or a band of duct tape. Starting about 2 inches from the end of the log, drill holes about six to eight inches apart down the length of the log; make a line of holes every three inches around the log. This will make a grid of holes in a diamond pattern around the log surface.
2. Insert your mushroom plugs
Tap your plug spawn into the holes using a mallet or hammer. You want them to sit just below the bark, flush with the wood of the log so there’s space left for sealing the holes.
3. Seal them in
Melt your sealing wax on low in a crockpot or an old pot (keep in mind the pot will be ruined for any future cooking). Dab melted wax over each plug with a paintbrush, using just enough to completely seal the plug.
WARNING: Hot wax can be flammable when overheated. Take caution when melting wax, and do not leave the paintbrush in the wax if the heat is still on.
4. Set your logs up
Keep your logs off the ground – you don’t want them to have direct contact with soil. This will help keep bugs and termites off. You can use three to four inches of gravel or a pallet to achieve this.
There are four ways to stack your logs: loose crib, triangle, lean-to, and upright.
5. Keep them happy
Water your logs once or twice a week to maintain moisture levels, unless they are regularly rained on. It’s important that you store your logs in the right place and keep an eye on them. Remember, mycelium are living organisms. If your logs completely dry out, the mycelium will die.
Setting up the proper habitat
You’ll want to set the logs up somewhere in the shade, especially during the incubation period (known as the “spawn run”). Tree canopies work great, or use an 80% shade cloth or cut pine boughs. You want to prevent them from getting too much sun in the summer months.
Additionally, keep them close to a water source, as you’ll need to wet the logs on a regular basis. If your area gets a lot of rainfall, lucky you! Otherwise, consider keeping your mushroom logs somewhere where a sprinkler will be able to reach them so you can water them easily when you need to.
Harvesting your mushrooms
Mushrooms fruit in response to stress, such as a decrease in nutrient levels, a rapid increase in moisture, or a sudden drop in temperature. When several of these changes occur simultaneously, they tell mushrooms that it’s time to reproduce. The first fruiting of your logs can be initiated nine to twelve months after inoculating them.
To get Shiitake to fruit, you’ll want to “shock” your logs first. To simulate the natural monsoon conditions of the native Shiitake habitat, submerge your logs in cool water for 24-48 hours (you can use a rain barrel, pond, or bathtub to do this, with a weight to keep them from floating). In about a week, mushroom buds (a.k.a. primordia) will emerge from the log and grow to maturity after another one to two weeks.
The best time to fruit your logs is in the spring, early summer, or fall, when daytime temperatures are between 50 and 75 degrees Fahrenheit. Once fruiting has begun, maintaining mild temperatures and high moisture will produce the highest yields and quality. In dry weather, mushrooms can harden and stop growing unless they are given a daily sprinkling of water.
To harvest, pull down the mushrooms by the stems or cut them close to the bark with a sharp knife. After fruiting for two to three weeks, the harvest will start to taper off. At that point, the mycelium needs a few weeks to digest more wood for the next fruiting. During this time, little watering is required.
After the resting period, another fruiting can be started. If you have multiple logs, you can stagger your soakings to get near-constant mushroom growth during the season! That means fresh, delicious gourmet mushrooms all season long.