Spent coffee grounds have all sorts of uses around the house and in your beauty routine. Instead of tossing yours in the trash after every pot, you could actually be salvaging them as garden fertilizer, natural pest repellent for your plants, skin exfoliation, and even cellulite treatment. But there’s one surprising way to reuse coffee grounds you probably haven’t considered: growing your own mushrooms. Edible varieties of fungi typically spring up naturally in damp forest environments, but did you know you can grow them right on your kitchen counter?
The idea of using coffee grounds as a growing medium for mushrooms isn’t entirely new. Mushrooms are notoriously hard to farm, popping out of the soil rather unpredictably and lasting only a few days. Home growers using countertop kits are more often than not disappointed with the results. The secret to growing success is actually in nourishing the root-like underground network of cells called “mycelium.” Coffee grounds are effectively pasteurized by the coffee brewing process, making them ideal for inoculating with mushroom “spawn.”
Oyster mushrooms are the easiest variety to grow at home. While you could order mushroom spawn from an online vendor and experiment with cultivating them in coffee grounds on your own, a few commercially available countertop kits make this process a lot easier. One is the HIFA coffee maker by Adrián Pérez and Mauricio Carvajal.
This all-in-one design functions as a French press-style coffee brewing station with a removable double-walled carafe. When you make your morning coffee, the grounds are automatically collected in the base unit, where they mix with mycelium to become a fertile substrate for mushroom growing. This design ensures optimal darkness and humidity conditions to encourage healthy, bountiful results. Then, you harvest the mushrooms directly from the front of the unit by cutting at the base of the stems, leaving a little piece behind to inoculate the next crop. It takes about a week for the tiny mushrooms to appear the first time around, and they double in size every day over the following week. When the substrate compartment is full, simply empty it and dispose of the grounds however you normally do, whether that means composting them or adding them to your garden beds.
While the HIFA mushroom-growing coffee maker is currently just a concept, a similar product—albeit one that won’t make you coffee—is already on the market. The GroCycle kit allows you to grow oyster mushrooms at home in just 14 days. It’s essentially a cardboard box full of recycled coffee grounds that have already been inoculated with mycelium spawn. You can order one online, and when you receive it, you simply open the box window and cut a hole in the grow bag. Spray it with water twice a day, every day, and watch the mushrooms grow.
Want to make use of the grounds you already have, instead of ordering them online? GroCycle also sells the “spawn,” though it’s only available for delivery within the UK. You can also find mushroom spawn of numerous varieties on Amazon or through the Forest Organics website.