Avoid a Pest Nightmare by Using Spent Fruiting Blocks

We produce hundreds of fruiting blocks weekly, and once they’ve grown one or two flushes, they’re discarded and replaced with fresh ones. The discarded blocks are often tossed into a pile, which will grow forever if it’s allowed to. To combat the risk of overflowing in mycelium, we’ve created a system for getting rid of old blocks. 

Importance of Getting Rid of Spent Fruiting Blocks

Before we developed our system of getting rid of our spent fruiting blocks, we got a gigantic pile built up. All the empty spaces that developed, the grain, the substrate, and the plastic shelters worked together to create a fantastic rat habitat. When the rats were discovered, there were dozens of them. It took a long time of fighting them off to get rid of the problem fully, and we didn’t manage to before they destroyed parts of our garden. We were lucky that they didn’t get inside and cause more damage. 

Sell Spent Fruiting Blocks

We sell used blocks for $1 apiece, or $100 a truckload, which is 100-150 blocks. If someone shows up with their truck with a trailer attached, we’ll let them fill it for $100, not really counting how many they take. We’re not really concerned about the money at this point, just trying to keep the pile from getting out of hand again.

Use them in Garden Beds

If you’ve got a garden, especially one you sell produce from, it’s beneficial to get to know any local mushroom farmers. Mycelium is great for holding moisture in the soil, just make sure you speak with your source. There are mushroom businesses that use brine to treat their substrate. This adds salt and other substances that aren’t desirable for gardens. Using spent fruiting blocks in raised garden beds is incredibly simple. Every winter, they’re piled over the bed to where they’re spilling over. Then they’re allowed to just rot down until it’s time to plant something. The spent fruiting blocks are depleted of nitrogen, so Andrew uses urea to aid in the process of breaking them down.

Take them to the Landfill

This isn’t the most popular of uses for blocks. In fact, the only reason we do so is because our county has a methane production facility they’re building into the landfill. We’re able to dispose of our blocks under food waste and it aids in the production of power for the county. In most places this isn’t a viable option, however. 

Use Spent Fruiting Blocks as Mulch

These blocks are really hard and prohibit high amounts of plants growing through them when they’re fresh. Oyster mushroom mycelium in particular is known for killing off plants when it’s living. One of the things we do with these blocks is use them as mulch around our trees and between our raised beds. This saves us a lot of frustration since mowing between the raised beds is difficult. 

Insect Feed

Insects love spent fruiting blocks. When we were using a composter, it was always full of black soldier fly larvae. There are black soldier fly farmers who use spent blocks to feed their flies. The flies break down the blocks quickly and produce frass, which is a biodegradable material that is fantastic for farming. Mushrooms are also great at producing living soil by attracting beneficial insects. 

Bonus Mushrooms

The blocks that we fill our raised beds with produce copious amounts of mushrooms over the winter. We eat those mushrooms because while they’re incredibly high quality, they’re also full of bugs. We’re not bugged by needing to spend extra time cleaning them, but restaurants expect the mushrooms they receive to be clean and ready to cook. 

Even once their originally intended purpose is complete, mushroom blocks have plenty of value left. There are several ways to get extra use from them. Feel free to share your favorite uses for spent fruiting blocks with us.