Growing Mushrooms on Logs with Plug Spawn

Growing mushrooms can be intimidating when you're just starting out. Not only are there many different kinds of mushrooms you can grow, but there are many different ways! We're glad you landed here, because growing mushrooms on natural logs is our specialty here at Field and Forest.

Drilling mushroom logs
inoculating logs with plug spawn
Indoor Incubation and spawn run

Step 1: Selecting your Mushroom Logs

Plug spawn is great for beginners and smaller projects. For more information on other inoculation methods, different spawn types, and information on log health visit the Learn section of the website and our YouTube channel. For now, we'll focus on plug spawn.

The first step for any inoculation on logs is to, well, get the logs! Logs need to be cut from living trees while the trees are dormant. You can check out our video "What is Dormancy?" to find out why this is important. Logs should generally be 4-6 inches in diameter and 40 inches long. This allows for a reasonable spawn run time as well as an ease in handleability of the logs. Aim to get the logs as straight as possible so they don't roll while inoculating them.

Step 2: Inoculation Tools and Drilling

Once you have your logs, you will need a few more things including an 8.5mm drill bit , or 5/16ths drill bit and stop collar, a drill, your spawn, and wax. These items all conveniently come in a shiitake log starter kit.

Before you begin drilling your log, you will want to assemble your drill bit and stop collar. Your kit comes with a drill bit, stop collar, and hex key. Take your stop collar and slide it onto the bit down one inch, which is the size of a plug. Use the included hex key to tighten the collar.

You will want to drill in a diamond pattern, or a 4 to 6 inch by 1-2 inch drill pattern. Start two inches in from the log end and place holes about 4 inches apart down the length of the log. This is about 6-7 holes per row. Rotate the log and begin the second row about two inches below the first row. Stagger the holes so they are halfway between the holes that were drilled in the row before. Do this around the entire log. If you were to connect the dots between the holes it would create a diamond pattern.

Step 3: Inoculation

Once you've drilled the log, you can get to plugging! Inoculating with plug spawn is a popular choice among beginners and those inoculating less than 100 logs as it does not require any extra upfront costs of an inoculation tool. The process is straight-forward, just take a plug and tap it into hole with a hammer until flush with the bark.

Step 4: Waxing

The final step of the process requires that you wax over the inoculation points. You can either melt wax and cover the points, but often times while using plug spawn it's easiest to use plug wax. Plug wax is a pliable wax that the warmth of your fingers will warm up enough to allow your smear over the plug and lock in the moisture. You can then proceed to label your logs if you choose. Keeping a record of your strain and inoculation date can prove helping in following years!


Following inoculation, you will want to stack your logs in a low stack to incubate for the next 9-18 months (this timing is based on diameter of the log as well as strain). You can see a variety of stacking methods in our video "Stacking Logs for Winter Storage".

Keeping your logs in an area protected from the wind and sun will allow the mycelium to start to work its way through the log, turning the wood to valuable nutrition! Speed of colonization depends on several things including: Strain, inoculation rate, log size, and incubation temperature.

Logs can also be inoculated and stored in a moderately cool spot indoors to get a jump start during the winter months. This is a nice option if you want to get your logs done before the busy gardening season starts. For indoor incubation you will need a large plastic bag. Cut small Xs through the bag in the two upper quadrants to allow the log to breathe. Place the log in the plastic bag and place it in an area of your house, usually a basement, where the temperatures are between 55 to 60 degrees. Watch for condensation on the bag interior- condensation is good- it means the mycelium is working! Once you notice a lack of condensation and the log feels dry to the touch open the bag and lightly spritz the log with water, fold the bag back up and watch for condensation. As time goes on you will start to notice white growth on the ends of the log, and occasionally at the inoculation points. This white growth is the mycelium making its way to the log ends and signals a healthy log! You will want to repeat the spritzing and drying process until the outdoor temperatures are consistently above 50 degrees and you can take the log out of the bag and move it outside to a shaded, protected spot. Usually, spring weather will provide all the moisture the log needs for continued growth. Logs will fruit naturally later in the season, about 9 months after the initial planting.


Plug Spawn Pros:
Easy to inoculate, doesn't require any extra inoculation tool.
Plug Spawn Cons:
Longer Spawn Run, take several more months to get initial mushroom crop.