If you’re a composter then growing mushrooms on coffee grounds might for you! It’s easy, cheap, and makes good use of what might have been thrown out before. With just a few simple steps you can easily turn what was once a waste into delicious mushrooms.

Coffee Grounds as Mushroom Substrate

Coffee grounds have a surprising amount of nutrients in them even after being brewed. Their essentially a power packed collection of everything a plant would need to grow, so it makes sense that they would have a ton of great nutrition for mushrooms to survive off of.

Coffee grounds will work as a substrate for a lot of mushrooms, but they work best for oyster mushrooms. This is because oyster mushrooms will grow on anything fibrous and woody, but a lot of other cultivated varieties are more picky about what they need. While coffee grounds can be used for other types, typically they take longer to grow and are more susceptible to contamination. Because of this it’s best to only use coffee grounds as a cost savings method when they’re widely available.

Saving Coffee Grounds for Mushroom Cultivation

While you might think just piling up the coffee grounds would be fine, you actually need to take good care to preserve them for use. Since they’re such a nutritious substrate, bacteria and molds can easily colonize them and use up a lot of the good nutrients that would have been used to help your mycelium grow.

To prevent this it is best to store your coffee grounds in the freezer until you have enough to use. If you’re getting them from a coffee shop, be sure to use fresh grounds as soon as possible to ensure they stay clean of contaminants and full of nutrition.

Growing mushrooms on Coffee Grounds

If you plan on using coffee grounds as your substrate you can adapt most growing methods easily to accommodate them. You could do a simple bucket method, bags, or growing bottles. All work perfectly fine.

While you can treat them just like any other basic substrate, it is important to note that you should pasteurize or sterilize your coffee grounds if at all possible. Many people say that you can use them if they’re fresh because they were pasteurized in the coffee maker, but this isn’t necessarily true. Brewing a pot of coffee typically lacks the time required to clean the grounds to the standards necessary for a high chance of success. Any basic pasteurization or sterilization will be sufficient to clean fresh coffee grounds that were stored properly.

When you’re ready to inoculate be sure to shake up your substrate. Coffee grounds tend to be incredibly fine and can condense very easily. This clumping will lead to areas that are hard for mycelium to penetrate well and cause a lack of gas exchange. While this can be overcome with time, simply shaking up your substrate during inoculation is sufficient to prevent these problems.

Recycle Your Coffee Grounds!

Using coffee grounds to grow mushrooms is not only a cost saver, but it’s environmentally friendly. Here at insta mushrooms, we’re firm believers in composting and recycling and this couldn’t be any more perfect a method for both. If you grow some mushrooms on spent coffee grounds, let us know and share a picture with us on twitter @instamushrooms.