Mushroom cultivation on coffee grounds: plants, care & Co.

With a little patience and some coffee grounds, you can grow your own mushrooms at home. We show everything about procurement, care and harvesting of the forest dwellers.

In many places, coffee grounds end up in the garbage every day, or at least on the compost. It is still relatively unknown that the nutrient-rich leftovers from the daily cup of coffee are also ideal for growing a wide variety of edible mushrooms. In the following you will learn everything about growing mushrooms on coffee grounds.

As strange as it may sound: the funny forest dwellers can also simply be bred in the kitchen. We show below how to grow mushrooms on coffee grounds.

Coffee grounds for mushroom cultivation

The nutrient-rich coffee grounds are now being used more and more as a substrate for edible mushrooms, and for good reason. When we drink a cup of coffee, we consume just under one percent of the biomass of the original coffee bean. The rest remains as a fine, warm-smelling substrate. But instead of going to the garbage, it should rather end up in the bed and in the pots. Coffee grounds contain a particularly large amount of nitrogen and can therefore be used as fertilizer not only for fungi but also for plants. The organic matter is also readily and quickly decomposed by microorganisms in the soil and is then available to the plants. An article specifically for using Coffee grounds as plant fertilizer you'll find here.

Another advantage for mushroom cultivation is that the coffee grounds are freed from harmful microorganisms such as mold and bacteria by the hot brewing. The coffee grounds from filter machines are particularly suitable for mushroom cultivation. There are hardly any antifungal substances left here, as is often the case with fresh beans. The leftovers from the self-grinding espresso machine are less suitable as a habitat for the fungi. The coffee grounds should not be more than two to three days old, otherwise the risk of mold growth increases again. Freezing fresh set prevents this to a large extent and so you can also build up a small stock.

How is a mushroom structured?

The fungus itself is invisible to us most of the time because it lives underground and rarely dares to surface. In beautifully moist and nutrient-rich forest soils, a real network of fungal cells, the so-called hyphae, forms under and between the roots of the trees. All cells together resemble a dense network of the finest roots and are called mycelium. The mycelium of the fungus communicates underground with neighbors and trees, digesting organic matter and releasing nutrients from the soil. When the conditions then become wetter, colder and darker - in our case, for example, in autumn - the fungus forms fruiting bodies. They then literally shoot out of the ground like mushrooms and delight many animals and human collectors.

The umbrella-shaped or spherical fruit bodies only serve the fungal mycelium for reproduction. Thousands and thousands of spores are thus released above ground for the next generation, and after a few weeks nothing more can be seen of the fungus itself. The mycelium networks can grow into real giants and sometimes weigh several tons and spread many square kilometers. For mushroom cultivation at home, the mycelium of the edible mushroom must be encouraged to form fruiting bodies.

Buy mushroom spawn: Recommended sources of supply

At the beginning of your own mushroom cultivation you need a little mycelium, which is usually on a small piece of wood or substrate. This dried, handy unit is also called mushroom spawn or inoculum spawn, as it is used to “inoculate” the substrate with the fungus and allow it to grow through. The starter mycelia are sold in various online shops, sometimes as streaky wooden dowels or loose in plastic bags. Mushroom growing sets with ready-made substrate can of course also be fed with coffee grounds.

There are many different offers for growing your own mushrooms circulating on the Internet. But also in some garden centers there are now growing kits for the most diverse types of mushrooms. We have selected some German sources for you.

mushroom pack For several years now, we have been sending various types of oyster mushrooms from Nuremberg, also as brood for breeding on coffee grounds. Additionally, the mycelia can be purchased locally in the city.

Mushrooms & Equipment Shop based in Münsterland has been offering a wide variety of species for hobby growers and commercial growers since 2013.

mushroom man from Saxony sends organically certified mushroom substrates - also especially for growing on coffee grounds. Propagation packages are now also available in the Dehner garden center.

Grow your own edible mushrooms

If you are now interested in trying your hand at growing mushrooms, you should be informed about the following aspects.

Which types are suitable?

There are many different types of fungi, some of which feed on wood, leaves or semi-decomposed organic matter. Here you can find out which species also thrive on coffee grounds in your home.

'oyster mushroom'(Pleurotus ostreatus): These tree-dwelling edible mushrooms grow in clusters from the substrate and form flat, depressed caps that are curled up at the edges when young. They are available in the colors dove blue, grey, white and light brown. They are also called veal mushrooms because of their consistency. Their taste is very fine and mild and is therefore very suitable for soups, sauces and meat dishes

'Lemon Oyster'/'Lemon Oyster' (Pleurotus citrinopileatus): Light yellow edible mushroom that is closely related to the oyster mushrooms, which can also be seen in the shape of the fruiting bodies. The taste is strongly reminiscent of lemon, which makes it very interesting as an accompaniment to fish or salads.

'Rose Mushroom' (Pleurotus djamor): Also called Flamingo Oyster because of its soft pink color. The mushroom is related to the oyster mushrooms and has a fan-like fruiting body covered with lamellae with a velvety surface and a fine mushroom taste. Versatile.

'shiitake' (Lentinula edodes): A fawn-colored edible mushroom with light-colored flakes on the round cap and a light-brown-whitish stem that is very popular in Asian cuisine because of its umami taste. Suitable for all kinds of dishes.

'Pioppino' / 'Southern Ackerling' (Agrocybe cylindracea): Brown-capped, medium-sized edible mushroom with a white stem that occurs naturally on poplars. It has a nutty, chestnut-like taste with firm flesh and can be used in a similar way to wild mushrooms.

Location and climate for mushroom cultivation

Cool places with around 10 to 15 °C and the highest possible humidity are particularly suitable for growing edible mushrooms. Mushrooms feel particularly comfortable in a mini greenhouse. Direct sunlight should be avoided, as should drying out the substrate. Mushrooms do need some light, but they only need moderate light to grow properly. If the substrate is by the window, care must be taken that there is no draught, because the mushrooms do not tolerate that at all.

Inoculation and maintenance of the mycelium

To begin with, dry substrate must be soaked in water overnight to encourage the mycelium to grow. Inoculated wooden dowels are usually moist enough to stick directly into the coffee grounds. The moist substrate is now mixed in a bowl with coffee grounds. The ratio should be about 8:2 coffee grounds to seed substrate. In addition, fine wood chips or straw loosen up the mixture and ensure a balanced water balance. The mixture is now filled into a flower pot, a bag or a large glass and only slightly covered so that air can still get in. Alternatively, you can drill holes in the lid or pierce the bag with toothpicks. Now the mycelium must be allowed to grow through the entire substrate. This takes about two to three weeks, during which time you always have to ensure that there is sufficient moisture and, if necessary, simply add some cold tap water. However, waterlogging must be avoided at all costs, otherwise the mycelium can die off. Now you should be patient, because after another 10 to 14 days the first fruiting bodies will gradually appear. In the case of bags, the plastic must be cut in an X-shape with a sharp knife so that the mushroom culture has space to grow out.

harvest mushrooms

As soon as the first mushrooms shoot out of the ground, you can start thinking about the harvest. In some species, such as oyster mushrooms, the edge that curves downward slowly unrolls with increasing size and then tears. Now is the perfect time to scoop out the mushrooms, either with a sharp knife or simply by hand with a slight twisting motion. It must be harvested at the latest when the spores of the fruiting body have fallen out and are visible as a brownish-grey coating under the caps. Because now the fungus has fulfilled its purpose and dies off within a short time.

Once all the fruiting bodies have been harvested, the substrate should be allowed to soak up plenty of water. After a while, it will bear fruit again. After about one or two harvest waves, depending on the quantity, the nutrients in the coffee grounds are largely used up and have to be refilled. The leached substrate can now be used as mushroom spawn and mixed with fresh coffee grounds, fill several vessels. So you not only get your own edible mushrooms, but you can also easily multiply and pass them on.

Using the fresh mushrooms

Unfortunately, the freshest mushrooms that you can get do not keep very long and should therefore be stored in the refrigerator and eaten within three days. Of course you can freeze, dry or pickle your own harvest to enjoy it for longer. However, the taste lasts best if the extraordinary plants go directly into the cooking pot. However, edible mushrooms can also be eaten raw and thus ensure a unique taste experience.

Find out how to grow mushrooms on tree trunks as an alternative in our special article here.