Learn how to make mushroom spawn at home on a mushroom grow log to kick-start your backyard permaculture forest.
If you’re fascinated with mushrooms and want to establish your own permaculture forest, you’ve likely wondered how to actually go about it. Many edible mushrooms, such as oysters and lion’s mane, can be grown in buckets indoors or outdoors. The bucket method is a quick way to get a great harvest, and it can often yield several mushroom harvests in a short amount of time. If you love the concept of adding mushrooms to your outdoor growing areas or even tending a permaculture forest full of fungi, it’s time to start exploring how to make mushroom-growing logs.
Mushroom Grow Log Prep
From plug spawn to logs, here’s what you need to know to get started.
Use hardwood logs. The tree needs to be living when the wood is cut so it has good moisture in it. Additionally, dead trees may already have other types of competing fungi colonizing the wood, so you don’t want to use those. Mushrooms tend to grow into the log best if some time has passed after it was cut, and 4 to 6 weeks post-cutting seems to be ideal. Beyond cutting the wood yourself, this project is a great way to use trees that have fallen in storms – talk about a silver lining!
Cut the log to any length that’s a good fit for the space you’re planning to put it in, though 3 to 5 feet long is a good place to start. For width, at least 6 inches is good. You can experiment with smaller logs, but their cycle of production may be shorter. If you’re growing in an urban setting with limited space, or even on an apartment countertop, experimenting with smaller logs is definitely worthwhile. When you choose your log size, think about the ease of moving the logs around and where you want to place them.
Research the mushrooms you want to grow and which wood they prefer. Many do well on hardwoods, such as oak, maple, and elm, and some do well on fruit trees. Not as many mushrooms like to grow on evergreens or softwoods, so it’s important to check. Or, if you’re going to use a tree that’s fallen on your property, reverse engineer it and use a variety of mushroom spawn that appreciates the type of wood you’re working with. Check out Choose the Right Wood for Your Mushrooms below for a quick reference guide on which mushrooms prefer which type of wood.
Buy or make mushroom spawn plugs. You can order these from several mushroom companies, or make your own using liquid mushroom culture, rice, and hardwood dowel pins. If you’re doing just a couple of logs, ordering premade plugs may be the way to go. If you want a larger number, you’ll save money by making your own plugs, and it’s a fun process to learn. Whether you’re ordering or making your plug spawn, make sure it’s ready to go 4 to 6 weeks after your logs were cut or downed in a storm. Most of the time, your homemade plugs can be ready within 4 to 5 weeks.
Use beeswax or cheese wax. In a pinch, you can use other waxes. Melt your wax and pour it over each hole to seal the plugs in the log. This will help keep hungry critters, such as chipmunks, out of the log while keeping the mycelium in the log so it can colonize thoroughly.
Choose the Wood for Your Mushrooms
Mushroom Type, Preferred Wood Types, and Time Frame to Harvest
- Oyster varieties-Beech, Elm, Maple, Oak, Poplar; 6 to 12 months
- Lion’s mane-Beech, Maple, Oak; 12 to 18 months
- Shiitake-Beech, Maple, Oak, Sweetgum; 12 to 24 months
- Reishi-Birch, Elm, Maple, Oak; 12 to 24 months
- Turkey tail-Beech, Birch, Maple, Oak; 9 to 18 months
- Maitake (hen of the woods)-Elm, Maple, Oak, Sweetgum; 24 to 36 months
- Nameko-Beech, Elm, Maple, Oak; 12 to 18 months
- Chestnut-Beech, Maple, Oak; 12 to 18 months
Make the Mushroom Spawn
If you’re lucky and have a good pressure cooker, it’s the perfect tool for making mushroom plug spawn, but if you don’t, you can still make your own using my stovetop technique. These methods work great with lion’s mane, reishi, turkey tail, oysters, and quite a few other types.
There’s no hard rule about what size the plugs should be. I prefer to use hardwood dowel pins that are about 5/8 by 1-1/2 inches – at the end of the day, the goal is just to get well-colonized plugs into the logs. You’ll want your plugs to be big enough to have sufficient surface area for the mycelium to grow onto, but also small enough to make them easy to install in the logs.
For an 8-inch thick log that’s about 3 feet long, use about 50 mushroom plugs. When I’m making plug spawn for growing my mushrooms at home, I generally try to make a few hundred at once so I can do several logs in one go. If you don’t want to make more than one mushroom log, plan accordingly – or make extra to share with friends!
Whether you’re using a pressure cooker or doing the stovetop method, soak your hardwood dowel pins in water overnight.
Pressure-Cooking Method
- Fill a quart-sized canning jar about halfway full of hardwood dowel pins, add about 4 tablespoons of uncooked brown rice on top, and add 1/2 cup of water – there should be about 2 inches of space for things to expand.
- Drill a small hole in the jar lid and tape over it with paper bandage tape. The tape will allow some exchange of air and moisture and keep everything healthy.
- Put the lid on the jar and pressure cook at 15 psi for one hour.
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- Allow everything to cool to room temperature, drain the excess water, and add 1 milliliter of liquid mushroom culture. Put the lid back on and let it sit for a few weeks.
- When you begin to see fluffy white mycelium growing on the rice, shake up the jar to help the mycelium distribute throughout the plugs and make your spawn colonize faster. Once all of the plugs are covered in mycelium, they’re ready to use!
Stovetop Method
- After you’ve soaked your hardwood dowel plugs in water overnight, transfer them to a large pot (a Dutch oven is best) and allow them to sit at a low boil with the lid on for about two hours. At the end of the two hours, turn off the heat.
- Cook about 4 tablespoons of brown rice. While your pot of plugs is still hot, drain the water, and put your plugs in a quart-sized freezer bag, filling it about halfway.
- Put the brown rice on top of the hardwood plugs in the bag, squeeze out all the air, and let it cool.
- Once everything is cool, add 1 milliliter of liquid mushroom culture. Instead of sealing your plastic bag, cover the opening with paper bandage tape. Let your bag sit for a few weeks the same way you would with the pressure-cooker method.
Note: Instead of a plastic freezer bag, you can use a sterile glass jar. Drill a hole in the lid and cover it with bandage tape.
When your plug spawn is ready, it’s time to make your logs.
Make the Mushroom Logs
- Drill holes in your log. Make sure your drill is well-charged, and that your drill bit is the proper size. You’ll want to make the holes about a quarter-inch deeper than the length of the plugs, and a bit wider. You won’t want your hole so small that it scrapes off the mycelium when you put the plug in the log, but you also won’t want it so big that the plug is loose in the hole. Space the holes evenly across the log, a few inches apart. It’s fastest if you drill all the holes first and then add all the plugs instead of doing each step one mushroom plug at a time.
- Insert your plug spawn. Depending on the size difference between the plugs and your drill bit, it may be easy to pop them into the holes in the log by hand, or it may take a gentle tap with a hammer. If it takes more effort than a light tap, you should get a slightly larger drill bit.
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- Melt the wax. I generally apply all of the wax in one go as well. Put your wax in a metal coffee can in a pan of simmering water (or in a double boiler you can dedicate to this use) and carefully melt it. Next, use a spoon to pour just enough wax over each plug hole to cover and seal it.
- Put your logs where they won’t be disturbed. I prefer a nice shady spot near trees, but as long as your logs aren’t in direct sunlight, they’ll be okay. We usually stack them, but you can lean them up against each other or even use a post- hole digger and put them upright in the ground. Get creative and have fun as you design your permaculture forest!
- Be patient. Mushroom logs can take as little as a year or as long as three years to show any signs of mushroom growing. Mushrooms like oysters and lion’s mane are quicker, while turkey tail and shiitake are on the slower end of the spectrum. The great reward is the longevity of your mushroom logs – you can often harvest for years once they get going.
If your mushroom log has been sitting for a long time and isn’t showing any signs of action, try soaking it in a trough of water overnight. Shiitake logs can often be kicked into action by hitting the end of the log with a hammer; a few good thunks will do. It simulates a branch falling out of a tree and lets the mushrooms know it’s time to grow.
Harvest Time!
When your mushrooms grow, always make sure they look like the mushrooms you intended to grow. It’s not usually an issue, but if they look different from what you meant to grow, take time to confirm the identification with 100 percent certainty. Share photos of the cap, gills, and stem with the place where you purchased your plugs or culture, or have a local mushroom expert check them out – and then share your harvest!
Originally published as “Growing Mushrooms from Plug to Harvest” in the October/November 2024 issue of MOTHER EARTH NEWS magazine and regularly vetted for accuracy.
Erin Hamilton is the founder of The Mushroom Conservatory. Through her innovative mushroom-growing kits and workshops, she has taught thousands of budding mycologists how to grow mushrooms and start businesses.
