Growing Mushrooms on Coffee Grounds in 3 Steps
Used coffee grounds are an excellent substrate for cultivating oyster mushrooms. By growing mushrooms on coffee grounds, you turn a waste product into a high-quality food source. Best of all, this method is simple, low-cost, and ideal for beginners.
Why Coffee Grounds Work So Well
One major advantage of coffee grounds is that the brewing process already nearly sterilises them, so you do not need to pasteurise or sterilise them before inoculation. However, always use coffee grounds as fresh as possible – they start to develop mould within just a few days.
At room temperature, process the coffee grounds within two days. When refrigerated, they last considerably longer. You can also extend their shelf life by drying them in an oven. Before use, simply rehydrate the dried coffee grounds with water.
Materials & Equipment
- Coffee grounds
- Fruiting container (e.g. plastic bag)
- Cable ties or clips
- Mushroom spawn
Step-by-Step Instructions
1. Prepare the Substrate
Mix dried coffee grounds with water before use and make sure the water is fully absorbed. Free-standing water encourages mould growth, so drain any excess carefully. Since coffee grounds are often too dense on their own, mix them with straw to improve aeration and give the mycelium room to breathe.
2. Fill the Fruiting Container
You can either layer or pre-mix the substrate before filling the container. To pre-mix, use a tub, rotary composter, or cement mixer – thoroughly clean and disinfect it before and after use. For layered filling, alternate 5–8 cm layers of substrate with 1–2 cm layers of mushroom spawn until the container is full.
3. Seal the Container
Finally, seal the container firmly with a cable tie, clip, string, or similar. After sealing, place it in a warm, dark spot and wait for the mycelium to colonise the substrate.
Want to discover more mushroom cultivation techniques? Join one of our workshops and we’ll show you everything you need to know.
