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, a waste product is transformed into a high-quality food source.

One major advantage of coffee grounds is that the brewing process already nearly sterilises them, so they do not need to be pasteurised or sterilised before inoculation. However, it is important to use the coffee grounds as fresh as possible, as they start to develop mould within a few days.

At room temperature, coffee grounds should be processed within two days; when refrigerated, they last longer. Another method to extend their shelf life is drying them in an oven. Before use, the dried coffee grounds must be rehydrated with water.

Materials & Equipment:

• Coffee grounds
• Fruiting container (e.g. plastic bag)
• Cable ties or clips
• Mushroom spawn

Steps:

1. Dried coffee grounds must be mixed with water before use. The water should be fully absorbed by the coffee grounds. Free-standing water encourages mould growth. Another challenge is that coffee grounds are often too dense. Better aeration of the substrate can be achieved by mixing coffee grounds with straw.
2. The substrate can be layered or mixed before filling the fruiting container. If the substrate is to be mixed beforehand, a tub, a rotary composter, or a cement mixer can be used. These must be cleaned and disinfected before and after filling. In layered filling, alternating layers of 5 – 8 cm of substrate and 1 – 2 cm of mushroom spawn are placed into the fruiting container.
3. The container is then sealed with a cable tie, clip, string, or similar.

You can learn more mushroom cultivation methods in our workshops.