Growing Shiitake Mushrooms 101

[HOMEGROWN.org]

The following 101 on inoculating and growing shiitake mushrooms comes from HOMEGROWN member Allen, the proprietor and Renaissance man behind Cosmo Farm, in North Carolina’s Pisgah Forest. Thanks, Allen, and please keep the good ideas brewing!

When trying to find things to grow on my small homestead farm, I looked around to see what was naturally thriving in the mountains of North Carolina. I saw that blueberries grow wild, so I started with 125 blueberry bushes. Then I thought of apples, since I see lots of wild crabapple trees. The problem, though, with domesticated apples and other fruit is that I happen to live in an area that’s considered a temperate rain forest. This means we get about 80 inches of rain annually. That much rain makes it difficult to grow things like fruit and berries due to diseases caused by fungi and molds.

Well, I thought, if fungi like to grow here, then that’s what I’ll grow. Why fight Mother Nature? After doing a little research, I found that I would need oak logs, shade, and water to grow mushrooms. My wooded acreage provides me with all of the oak and shade I need, and several creeks and lots of rain provide the water.

So, where do the logs come in? The mushroom spores get inoculated, or injected, into the logs, where they live and grow. Inoculating logs is similar to a person getting inoculated with a vaccine, but in this case, the log is being injected with spores. Think of the logs as the mushrooms' host, but also as their food and soil. The job of the mushrooms is to decompose—that is, to eat—the wood. If it weren’t for mushrooms, we'd be up to our eyeballs in fallen trees.

In my first year, I inoculated 25 logs as a test run. Those produced very well, so every subsequent year I have added additional logs to increase production and replace depleted logs. Logs should last from three to eight years, depending on the size and type of wood used. I started giving mushrooms to friends, using them for barter, and selling them to a local restaurant. I also eat lots of fresh mushrooms and dehydrate them for off-season use.
This year I’ll even be at the local farmers market, as I approach 200 logs in production.

I decided to start with shiitake mushrooms, since those are the most popular of the do-it-yourself varieties. There are several other types of mushrooms that can be cultivated, each with its own technique, type of wood, and system (logs, stumps, straw bales, sawdust, you name it), but the information in the 101 below is specific to shiitake. Growing mushrooms requires a lot of elbow grease up front, but once the logs are inoculated, the work in the following years is minimal. Holding a mushroom inoculation party makes the work fun and quick, and everyone goes home with a log or two.

WHAT YOU’LL NEED

» Oak logs about 3 to 8 inches in diameter and 30 to 42 inches long. Just remember that you’ll have to pick them up and move them around, and the larger ones tend to get heavy, especially when wet. Shorter logs tend to dry out faster, so choose your logs according to your lifting capabilities. You can also use other types of trees, such as maple, ironwood, sweetgum, and other hardwoods, but red oak or white oak is best. (Shiitake means “mushroom of the oak” for a reason.) Maple bark doesn’t hold up as well as oak, and maple won’t last as many seasons as oak. There are certain types of trees you just shouldn’t use, such as any conifer, soft hardwood, locust, black walnut, ash, or elm. If you’re unable to cut logs yourself, you can order them from a firewood supplier. Just make sure you’re getting fresh logs.

» Mushroom spawn, in any of several forms. The spawn is mushroom mycelium mixed with some type of substrate. I purchase sawdust spawn, which is best for preparing a lot of logs, but you can also get wooden dowels that contain the mycelium, which is easier for small runs. Mycelia are spores, which is basically like the seed of the mushroom. When in contact with a suitable food (e.g., wood) and the right amount of moisture, it grows and produces fruit (a.k.a. mushrooms). Spawn may be stored in the refrigerator for several months. Since suppliers can’t always ship your spawn immediately, order in advance and you’ll have it when you need it.

» Tools, such as a drill and an inoculating tool if you’re using sawdust spawn or a hammer if you’re using dowels. I use an angle grinder that has been outfitted with a special bit to drill the correct diameter and depth for my inoculation tool. If you’re only inoculating a few logs and using dowels, it’s fine to drill holes with any drill. But if you’re inoculating quite a few logs, it’s worth the investment to get the angle grinder and special bit. Your wrists will thank you, and you'll save hours.

» Wax to seal the holes once the log has been inoculated. I suggest using cheese wax. I once used beeswax only to have it melt in the summer and leak out of the holes. I use a dedicated $5 crockpot from Goodwill to melt the wax and a special dauber to apply it, but you can use any small paintbrush.

» A shady and cool spot to store your logs; 80 percent dappled shade is just about right. if you’re in a dry area, you’ll also want a spot protected from the wind.

» Water to soak the logs. I store my logs next to the creek and throw them in when needed, or I let the rain keep them wet. If a creek or pond isn’t available, you can use a garden hose with a sprinkler or occasionally submerge them in any tank of water, such as a stock tank, a 55-gallon drum, or an old bathtub.

 

WHAT TO DO

1. Cut your logs to size. This is best done when the trees are dormant, as the bark has a better chance of staying tight, so plan to cut them in winter or early spring, about a week before inoculating. Don’t use tree limbs that have fallen or any tree that shows signs of decay or disease. And don’t let the logs sit on the ground for too long, as they will pick up mushroom spores from other strains that will compete with or kill your spawn.

2. Drill holes according to the type of inoculating method you’re using. Holes must be drilled to the diameter and depth as set forth by the dowel or plunger type of inoculation tool. Instructions will come with whatever type of inoculate you order. Do not predrill holes with the idea that you’ll come back and fill them later. Only drill what you can fill and seal in a short time. Holes should be drilled in a diamond pattern: Drill a lengthwise line of holes 6 inches apart and then roll the log about 2 inches. Drill another set of holes 6 inches apart, staggered with the previous line of holes, thereby creating the diamond pattern. The pattern isn’t critical. You just want to get the spawn spread out evenly throughout the log.

3. Insert the spawn. Per above, the spawn can either be on dowels for small jobs or in sawdust form for larger jobs. Use the special plunger tool with the sawdust spawn. Make sure that the hole is neither under- nor overfilled. The top of the spawn should be slightly indented, leaving room for the wax seal.

4. Seal the holes with cheese wax. Make sure the hole is thoroughly sealed to keep the spawn from drying out and other spores from entering the log. Be careful not to overheat the cheese wax, which can ignite if it gets too hot. A crockpot is usually safe.

5. Set your completed logs in the shade. Since I’m in a very wet area, I stack my logs up off of the ground on other oak logs or pallets to keep foreign spores from entering. Remember, you’re aiming for shade dappled with sunlight, about 80 percent shade. Logs must not be allowed to dry out during incubation, or the mycelium will die. In dry areas, keep them close to the ground.

6. As the logs incubate, the mycelium you have injected will begin to grow and form a network of tiny roots. When the temperature and moisture content is right, the logs will start to “pin,” or show signs of mushrooms. Contrary to popular belief, the mushrooms do not pop out of the holes that you drilled but can form anywhere on the log. Fruiting usually begins in autumn if it’s not too cold, if other conditions are right, and if you have used sawdust spawn. Doweled logs usually produce one year after inoculation. Some strains do better in warmer weather, some in cooler. I use a broad-range strain, which produces in a wider variety of conditions.

7. When the logs are ready to produce, soak them for about 24 hours then remove them for forced fruiting or just wait for a heavy rain. There are different ways to stack them, but I usually stack mine log-cabin style. As in my case, too much rain while mushrooms are growing can cause them to get soggy. I sometimes need to cover the logs with a tarp while they are fruiting.

8. The mushrooms are best picked while the caps are still curled under. If left on the log too long, they flatten out and begin to deteriorate. I recommend checking your logs frequently, especially in wet weather, as I have often been surprised by a huge flush of mushrooms.

9. Just as you like mushrooms, so do a host of other creatures, from slugs to squirrels to other furry friends. You can set beer traps for slugs. I am trying ducks this year, as I hear that ducks love slugs. The biggest danger to your logs is that they become too dry, so make sure to maintain proper moisture content.

Keep in mind that, as with any crop, what you do depends on many factors, such as climate, type of wood, and strain of mycelium used—some of which may be quite different from what I have described. Do a little local research to see what works best in your neck of the woods. And don’t be intimidated. The logs will pick up mycelium with or without your help. This is nature’s way of decomposing wood fiber. All we're doing is helping the logs grow the kind of mushrooms that are good to eat.

MORE RESOURCES

If you want to dip your toe into the world of mushroom growing but the above process sounds like more of a commitment than you're ready for, you can buy a small starter kit with everything you'll need for about five logs. You can even get a tabletop farm to stick in your kitchen garden that is guaranteed to produce mushrooms.

While there are many suppliers of tools and spawn, I recommend the two below from personal experience. Both of these companies can also provide you with books and free information to help your inoculation go smoothly.

» Field and Forest Products: 800-792-6220

» Fungi Perfecti: 360-426-9292

And for further reading, I recommend this downloadable PDF on growing shiitake mushrooms from the North Carolina State University Cooperative Extension. Good luck and have fun!

SPEAK UP!

Got a question for Allen? A tip to add? Or even a spore joke? Post it below and keep the conversation rolling. You might also be interested in 101s on finding morel mushrooms or catching wild levain. You might consider joining the Hunting, Gathering, and Foraging group. And you can always find more things to plant, grow, make, craft, cook, preserve, and inoculate in the HOMEGROWN 101 library.

ALL PHOTOS: ALLEN FROST

[Alison Gillespie]

What a great post!  I, too, have enjoyed growing mushrooms -- but in my very urban and very tiny basement here just outside of DC.  We used one of those small kits you describe toward the end of your post.  Our goal was to have fun growing an edible with our kids. If you want to read about that adventure you can see my blog post about it at http://whereyouareplanted.com/growing-shitake-mushrooms-with-kids/    I admire your in-depth look at the larger scale process and I'm going to show this to my kids so they can see how it is done when done big!  Thanks again.

[Jennifer]

Alison: Thanks for sharing this post! I don't know what's cooler: that your daughter loves mushrooms or that it was her idea to grow them in the first place. Both seem pretty fantastic! Did you like the kit you used enough to recommend it? If so, where did you find it?

[Alison Gillespie]

We ordered ours from Cooks Garden catalog.  You can visit their site: http://www.cooksgarden.com/  I just checked and they are selling the kit again this year as well as one for portabellas.  It was a great kit.  Had everything we needed -- literally comes in its own case for growing, etc.  I don't think we did a good job of maintaining it over time.  (Note my original post was in 2010.)  We are ordering another one this year.  Still, for the money we got a LOT of mushrooms in 2010.  Oh, and hey, I truly think my daughter's love of mushrooms grew with the kit.  She  liked them to start with but there is something about growing your own food that makes kids really fall in love with food.  I've posted about that on other parts of Homegrown.  The same kid that never eats a salad at the table loves to sneak into the garden for pieces of mesclun mix and begs to pull carrots out of the dirt and wants to eat them with out washing them.  (Which I won't let her do.) Go figure.  

Jennifer said:

Alison: Thanks for sharing this post! I don't know what's cooler: that your daughter loves mushrooms or that it was her idea to grow them in the first place. Both seem pretty fantastic! Did you like the kit you used enough to recommend it? If so, where did you find it?

[tvanhorne]

Awesome!  I've always wanted to grow shiitake but just haven't started yet.  Thanks for the information--very clear and helpful.  Maybe I'll get started this year!