For the past six months or so I’ve been learning how to grow Oyster mushrooms, mostly by trial and error, and I feel like I’ve finally gotten the hang of it. In this post I’m going to cover a bit of what I’ve found.

First, there are three things you need to start:

  1. Some mushroom mycelia of the variety you want to grow.
  2. A medium you want to grow on (e.g., coffee grounds, old wood, etc.).
  3. A container to grow in.

You won’t need a container to grow in if you’re growing on logs, but since I’m using coffee grounds I got a few 5-gallon buckets. Right now I’m growing Grey Dove Oysters. There are vendors out there that sell sawdust spawn or grain spawn—mycelia grown on sawdust or grain—and I’ve found that grain spawn is easier to work with because it propagates better to the medium. You can also try to start your own spawn from mushrooms or previous mycleial growth.

To get started, I cleaned the buckets out with hot (near boiling) water, then partially dried them. To the bottom I added a small amount of grain spawn—enough to get maybe 25% coverage—and then mixed in some initial coffee grounds. The coffee grounds should be added soon after the coffee was made, when the grounds are still steaming a little, because that ensures that mold and other things don’t start growing on it. After adding the initial coffee grounds, I added another small amount of grain spawn. I left the bucket in the shade but in the kitchen (where there’s a fair bit of airflow) for a few days for the initial mycelial growth to take hold. (I leave the bucket’s lid ajar a few inches.) After waiting a few days, I started on my daily schedule adding coffee grounds to the bucket.

Keeping the mycelia clean and at the right level of moisture is surprisingly difficult, but I’ve found that when in doubt, aim for more cleanliness and less moisture. The reason is simple: mold. The environment that the mycelia like to grow in is also one that mold likes to grow in, but mycelia can withstand drier conditions and application of hydrogen peroxide.

Another thing I’ve realized is that one’s nose is the best guide. If the mushroom culture smells good (sometimes like mushrooms, though usually just a faint sweet smell), then it’s doing okay. If it smells bad in any way—and it’ll cause a natural reflex when it’s bad, so you don’t have to overthink it—that’s a sign mold is starting to take over. If that happens, give the culture a lot more air, and (optionally) spray it down with some hydrogen peroxide. You can even set it out in direct sun for a few hours.

I also tried growing a bit of mycelia from scratch on some cardboard. I stirred the cardboard in boiling water for about 20 minutes to kill any mold and to break down the structure a bit. I then took some mycelia I already had and placed bits of it between the (now broken-down) layers of cardboard, and sandwiched them together. I placed the cardboard layers in a small trash can and covered it with a book, with minimal air gap. Since the cardboard had little that mold was interested in, it didn’t get moldy like coffee grounds tended to in a similar low-airflow environment. Mycelial growth was slow: I checked on it every few days and found that it took about a month before the white spiderweb-like mycelia was visible between all the layers. I ended up not using this cardboard for further growing, but it was fun to try out.

I’m hoping to try out growing on old logs in the near future. As for the sustainability of coffee…well I’ll have to write about my nascent attempt at growing coffee another time.

Leave a Reply


There aren't any comments at the moment, be the first to start the discussion!