Using Coffee Grounds to Grow Oyster Mushrooms

Coffee grounds are a waste product for coffee houses, cafes, and restaurants, but are a great substrate for growing oyster mushrooms. Unlike log culture, oyster mushroom mycelium can run on fresh coffee grounds rather quickly and fruit much sooner, and unlikestraw culture, fresh coffee grounds do not have to be pasteurized to remove competing microbes since they have been run through a coffee machine.  By using coffee grounds as your growing medium, you can enjoy fresh mushrooms in about 5 weeks.

What you need:

Fresh, used coffee grounds (no more than 1 day old)

Oyster mushroom spawn 

Filter Patch Grow Bag (substitute cleaned out plastic milk jug, large freezer bag, or small plastic bucket of some sort).  If you don’t use the grow bag, make sure that you have poked or drilled four air holes in your container.

Large Mixing Bowl

Spray bottle

The Process:

1. In your large mixing bowl place fresh coffee grounds and oyster spawn together in a 3:1 ratio

2. With your hands mix the oyster spawn into the grounds.  Really make sure you break up any large pieces and get it even.

3. Place your mixture in your growing container so that it is around 3/4 full.

4. Place the growing containers with the inoculated coffee grounds in a warm dark place for three weeks.  Mark your calendar or set an alarm on your phone to remind you to check them.

5. After 3 weeks the mixture should be completely colonized with white oyster mushroom mycelium, and ready to fruit.  Note-if your mixture was contaminated with mold during inoculation, the grounds weren’t fresh, or your spawn was bad, you might find patches of green mold.  Not good. If it’s only a little spot you might be able to kill it by sprinkling salt on the area, if it is throughout the whole container, you might have to compost it and start over.

6. Ready to fruit! Make a two inch diameter hole in your container or bag and place the container in an airy spot with indirect light. A humid location is good.

7. With your spray bottle, spritz inside the container twice per day.  Don’t allow the mushroom container to ever dry out.

8. After about a week little mushrooms will begin to appear, after one more week, they will be ready to eat! YUM!


To find locally grown mushrooms in your area, visit!

Photo by Laura Berman

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