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Mushroom Logs


It seems like our trees can’t catch a break. Here we are, in the middle of June, and we are still seeing some serious branch collapse and, here and there, entire trees tipping over, root ball and all—only this time, it’s due to the regular waves of heavy rain, wind, and thunderstorms putting pressure on old trees fortunate to still be standing after the winter. So, again, many of us are having to limb up large trees and have a bunch of logs we don’t know what to do with.

We touched briefly on some ways you can reuse your yard waste, like big branches, in a previous article. With the smaller stuff, you can make tomato cages, trellises and arbors, and a lot of cool crafts for the home and garden. The wider stuff is another story. What do you do with the big logs you sometimes end up with when you have to cut or trim a tree?

To read about what it takes to transform a tiny bit of spore into a flush of healthy edible mushrooms, you might immediately walk away from any ideas you had about casually growing your own. Expert mushroom growers use equipment that most of us don’t have, and when it comes to preparing materials and observing the progress of mycelium colonization and mushroom growth, they are anything but casual. In short, it is a lot of work to grow a mushroom from start to finish.

Now, there is a way you can grow mushrooms without investing in special equipment and tools or pasteurizing your growing substrate, and that involves logs. Using a freshly cut log is a great way to grow mushrooms, especially for a beginner or someone that wants to be able to set them up and walk away. While not all mushrooms will grow this way, several common edibles will flourish when properly inoculated into a log, including oysters, shiitake, maitaki, reishi, and lion’s mane, and it is all done with plug spawn.

A mushroom spawn is an organic material that has been colonized by mushroom mycelium. This spawn is used to inoculate the growing substrate where mushrooms will ultimately be produced. Some mushroom spawn is made with loose materials, like grain or sawdust, which have been carefully sterilized and sealed into containers so that the mycelium can spread and grow. Plug spawn is mycelium that has been grown on a small piece of wooden dowel. These plugs are what you are going to use to inoculate your log. While you can attempt to grow your own plug spawn, it is easy and inexpensive to purchase ready-to-use plug spawn online (making your own spawn is a ton of work, and will require a sterilization process and constant monitoring for contamination).


A log, or lots of logs

Plug spawn

A drill and drill bit, 5/16 in.

A rubber mallet


A paintbrush

The Log

You aren’t going to want to use just any hunk of wood to start your mushrooms, and if you want your mushroom log to be successful, there are a few considerations you’ll need to take into account. Plug spawn tends to take the best on hardwoods, like maple and oak. This does not include conifers like pine or cedar as the oil in these woods have antifungal properties. The log you select should be around six inches in diameter and four feet long, but you can experiment with different sizes. This should be a log that you’ve cut and removed from the tree yourself, and not a piece of wood that has been sitting on the ground dead for a few weeks. The reason for this is dead logs are likely contaminated with another fungus already, especially if they’ve been laying around on the ground for a while. Cutting the wood yourself will also allow you to select wood that is healthy.

When you’ve cut your log, allow it to rest for around two weeks before proceeding to inoculation.


With your drill and bit, you will drill holes about two inches deep and four inches apart around your log. The best way to do this is in a diamond pattern. This is where you’ll be inserting your plugs. Place your plugs into the holes, and use the rubber mallet to gently tap them completely into the log, making sure that no part of the plug hangs out of the hole. Melt your beeswax in a double boiler or in a heat-safe bowl over boiling water. Using your paintbrush, cover each plug hole, as well as the ends of the log, in a layer of wax to seal.

The Waiting Game

At this point, you should find a shady, preferably humid place for your logs to hang out. You could stack them outside, line them up against a building, or stick them in the basement. This should be a place where you won’t mind keeping them for quite a while, as you aren’t going to see a mushroom for six months to a year. During this time, you will need to keep them moist by watering the log a few times a week. Every once in a while, check the ends of your log for telltale blackening—this is a sign that the log has become colonized with mycelium, and that fruiting is imminent.

Once the log fruits, you will be able to harvest from your mushroom log for at least four years 


Lentinula edodes shiitake:  Sakurai MidoriCC BY-SA 2.1 JP