Back in the spring, we embarked on our first mushroom-growing venture. So far, it’s yielded exactly one shiitake mushroom, but we have high hopes for a crop in the spring.
This is how you grow shiitakes: drill a bunch of holes in some oak logs; hammer in dowels infused with shiitake spawn (which you buy from Fungi Perfecti, or another supplier); leave logs in a shady spot. That’s it. Then you wait, and hope for the best.
What struck me, and might strike you, about this enterprise is how little work there is to be done. The only hard part is cutting down the tree. From there, it’s a cakewalk – and the mushrooms are supposed to keep fruiting for a good five years. As agricultural endeavors go, this one seems to have a very high reward-to-work ratio.
I’m sure it says something about me – something unflattering – that I choose crops to grow based in large part on how much work they are. True agriculturists, I suspect, enjoy the challenge of hard-to-grow foods and take pleasure in bestowing the attention required. But I’m not in it for the process; I’m in it for the food. Less process for more food is an unmitigated good.
Since shiitakes were so easy, I decided to branch out. Oyster mushrooms were reputedly good to grow at home, so I thought I’d tackle those. I bought myself a copy of The Mushroom Cultivator: A Practical Guide to Growing Mushrooms at Home, by Paul Stamets and J.S. Chilton and sat down to read up.
Let me summarize chapters 1-4 for you. Step One: Build a sterile laboratory.
Practical, my ass.
Building a sterile laboratory is way harder than cutting down a tree. Besides, it doesn’t play to my strengths. I’ve always tended to make hygiene – personal and household – a low priority, and that tendency has been exacerbated by living in the sticks, where I can go days without getting within three feet of another human being other than my husband, whose hygienic standards may be even looser than mine. (Still want to come visit?) A sterile laboratory is a pipe dream when you can’t even keep the bathtub clean.
I was thrown for a loop. Building a sterile lab is, for the time being at least, out of the question. Does that really mean that oyster mushroom cultivation is a non-starter?
Maybe not. There are three basic steps to mushroom cultivation. First, you use a spore to grow the beginnings of the mycelium (that’s the shaggy white stuff that lives below the surface, from which the mushrooms sprout) in a petri dish of agar. Second, you create spawn by using slices of the mycelium-infused agar to inoculate sterilized grain or sawdust, in which the mycelium continues to grow and really takes hold. Third, you use the spawn to inoculate a mushroom-growing substrate, in which the mycelium will reach maturity and then, with any luck, fruit.
Steps One and Two do require a sterile environment, but you can circumvent those steps by buying spawn, ready made, from Fungi Perfecti. Step Three, incolating the substrate, might possibly be accomplished without the lab.
I checked the Fungi Perfecti web site, and found that they sell both sawdust and grain spawn infused with the oyster mushroom mycelium (Pleurotus ostreatus, that is). The site emphasized that these products do not come with instructions, that you had to know what you were doing, and there was a purchase agreement you had to sign before you could buy the spawn.
A purchase agreement? For mushroom spawn? I clicked on the link. This is what it says:
I, the undersigned, acknowledge that I am an absolute bonehead who is bound to screw up the growing of mushrooms. Once I do, I will not hold Fungi Perfecti accountable in any way.
Not in so many words, of course, but that’s the gist. So let’s just say I went into this with low expectations.
I ordered the sawdust spawn.
One of the reasons I wanted to try oyster mushrooms is that I’d read on some crackpot website that you could grow mushrooms in the barley that’s left over from the beer brewing process. “Spent grain,” it’s called. I have the good fortune to know Beth Marcus who, with her husband Todd, runs Cape Cod Beer, and she told me that she’d love to see someone do something productive with the spent grain, and that I could pick some up any time.
Okay then. Once the sawdust spawn was en route to me from Fungi Perfecti, I had six days to research spent grain substrate in earnest. There’s not much to research, it turns out. A few people have tried it, and there are some sketchy online accounts of those attempts. The upshot seemed to be that spent grain is excellent – as a supplement to some other, less nutritious substrate, like straw. Because there are so many nutrients left in the barley, it’s an ideal host for the kind of bacteria, mold, and other nasty creatures that contaminate mushroom substrate. You shouldn’t use it by itself.
My best chance for success seemed to be mixing the spent grain with sawdust or chopped straw, but that brought me back to the sterilization problem – or at least the pasteurization problem.
If you’re not clear on the difference, you’re right where I was before I started reading about mushroom cultivation. Sterilization is heating at a temperature of about 250F, which kills everything known to man. Pasteurization is prolonged heating at about 170F, which kills most things that can contaminate mushroom substrate.
The key logistical difference between the two hinges on the fact that water boils as 212F. You can pasteurize stuff in boiling water, and that’s sufficient for substrate. Sterilization requires a pressure cooker or an autoclave (which is basically an expensive kind of pressure cooker).
Even though I do know how to boil water, pasteurization was one of the (many) steps I had hoped to avoid. Because the brewing of beer keeps the grain at the requisite temperature for the requisite time, I could get my substrate pre-pasteurized if I showed up at the brewery just as they were emptying the mash tun. If I had to combine the grain with another kind of substrate, one that needed pasteurization, I’d lose the advantage.
Best I could tell, here’s what I was supposed to do:
1. Build a sterile laboratory.
2. Arrange with Beth at Cape Cod Beer to arrive at the brewery to take the grain straight out of the mash tun. For this, I would have to bring a sterile container.
3. Obtain an equal amount of either straw or sawdust, and pasteurize it by boiling it in water in a large container on an outdoor burner for at least half an hour.
4. Drain the straw or sawdust, combine it with the spent grain, make sure the moisture content is somewhere around 65%, and wait for it to cool to 80F.
5. In the sterile laboratory, put the substrate in three-gallon plastic Ziploc bags. Wearing sterile gloves, open the package of sawdust spawn and distribute it through the substrate, at about a 1:10 ratio. Punch air holes in the Ziploc bags using a sterilized, stainless steel nail.
6. Put the bags in a dark, semi-sterile, climate-controlled room where the humidity is kept over 90% and the temperature is maintained at 80F.
7. Wait about a week for the mycelium to colonize the substrate, confident that you have done everything right.
Here’s what I actually did:
1. Cleaned the bathtub.
2. Arranged with Beth at Cape Cod Beer to arrive at the brewery to get a five-gallon bucket (theirs) of grain straight out of the mash tun.
3. Put the bucket in the bathtub, and transferred about a gallon of it to a three-gallon Ziploc bag, trying to take the stuff out of the middle of the bucket in an effort to avoid any contaminants that may have been on the bucket sides. Used my scrubbed hands and a thoroughly washed scoop.
4. Once the grain had cooled to about 90F, put the mushroom spawn bag full of sawdust spawn in the bathtub, and cut it open. Pulled a few cups of it out of the bag, using the same scrubbed hands, and distributed it throughout the grain in the bag. Punched holes in the Ziploc bag using a well-washed kitchen thermometer. In hopes of keeping the remaining sawdust spawn contaminant-free, re-sealed the special mushroom spawn bag with electrical tape.
5. Put the Ziploc bag full of inoculated substrate in a small cooler (to keep out the light, and to simulate the climate-controlled environment) and opened it periodically to let in fresh air.
This procedure had not a snowball’s chance in hell of succeeding. I was starting with the wrong substrate, and I it had many chances to pick up contaminants every step of the way. I was curious not about whether I’d get mushrooms, but just how the attempt would fail. Would it be mold? Would it simply be a failure of the mycelium to take hold? Would it be some strange bacterium?
That was four days ago. Imagine my surprise when I opened the cooler, took out the bag, and saw that the mycelium was beginning to colonize! There was white stuff in several patches of my substrate! And no smell of mold or hint of contamination.
I’m not out of the woods yet. Contamination can happen at any stage, and the chance that I’ll actually end up with mushrooms is still pretty slim. But you don’t need a sterile laboratory to dream.