Most specialty mushrooms in the US are grown on “blocks” or “artificial logs,” and we grow several varieties of mushrooms on these.
PHOTO BY: SCOTT STREBLE
Here’s how the blocks are made:
Woody or other agricultural materials such as straw are sterilized – usually with high heat. These materials are generally sterilized in a really tough plastic bag.
The grower adds mushroom mycelium (also known as “spawn”) to this substrate and seals the bag. The bag is kept at the right temperature and humidity and the mycelium eats its way through the material – which is food to it – in what we call “incubation.”
After a month or so, the mycelium has eaten all available material in the bag and the block is ready to grow mushrooms. There are many companies in the US (and around the world) specializing in creating blocks – which are generally sold and purchased at this stage. At Northwood Mushrooms, we purchase blocks from both Field and Forest Products (Peshtigo, WI) and New Hope Farmacy (New Hope, MN).
We place the blocks in an ideal growing environment and then harvest the mushrooms when they’re ready.
We have been growing mushrooms on blocks since 2020. Opening up this new growing method (new for us anyway) had several benefits. First, we are now able to grow a number of mushrooms that we weren’t able to before. This is because some mushrooms, like black poplar and chestnut, can’t be grown on logs. Second, as we experimented with different kinds of block-grown mushrooms, we found that some types of mushrooms, like Lion’s Mane, just grow so much better on blocks than they do on logs.
Mushroom blocks have also allowed us to grow mushrooms year-round. Mushroom logs (especially Shiitake) can be grown indoors, but we don’t believe this is feasible on a commercial scale in our climate. Blocks are much more space efficient, making them a viable alternative.
Some people have wondered why we don’t create our own blocks. Creating mushroom blocks is a whole different thing – involving lab work, sterilizing equipment, incubating rooms, and a whole host of other processes and equipment that we don’t have and don’t have the time for. It’s also not where our interests lie. So we let the folks who are interested in that part of mushroom cultivation do their thing, and we focus on our thing – growing and harvesting all these beautiful mushrooms!