Growing mushrooms on coffee grounds: planting, care & Co.

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

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

As strange as it sounds: The funny forest dwellers can also be easily grown in the kitchen. We'll show you how to grow mushrooms on coffee grounds below.

Coffee grounds for growing mushrooms

The nutrient-rich coffee grounds have recently been used more and more often as a substrate for edible mushrooms, and for good reasons. If we drink a cup of coffee, we only consume just under one percent of the biomass of the original coffee bean. The rest is left over as a fine, warm-smelling substrate. But instead of throwing it in the garbage, it should rather go into the bed and into the pots. Coffee grounds contain a particularly large amount of nitrogen and can therefore be used as fertilizer not only for mushrooms 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 will find here.

Another advantage for mushroom cultivation is that the coffee grounds are freed from harmful microorganisms such as molds and bacteria by the hot brew. The coffee grounds from filter machines are particularly suitable for growing mushrooms. It hardly contains any anti-fungal substances, as is often the case with fresh beans. The leftovers from the self-grinding espresso machine are less suitable as a habitat for the mushrooms. The coffee grounds should not be older than two to three days, otherwise the risk of mold growth increases again. Freezing fresh set prevents this to a large extent and so you can also stock up on a small amount.

How is a mushroom structured?

The fungus itself is invisible to us most of the time, because it lives in the ground and rarely dares to rise to the 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 taken 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 become more humid, colder and darker - in our case for example in autumn - the fungus forms fruiting bodies. They then literally spring up like mushrooms and delight many animals and human collectors.

The umbrella-shaped or spherical fruiting bodies serve the mushroom mycelium only for reproduction. Above ground, thousands and thousands of spores are released for the next generation, and after a few weeks nothing can be seen of the fungus itself. The mycelium meshes can grow into real giants and sometimes weigh several tons and reach many square kilometers. For mushroom cultivation at home, the mycelium of the edible mushroom must be made 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 dry, handy unit is also called mushroom spawn or vaccine spawn, as it is used to "inoculate" the substrate with the fungus and let it grow through. The starter mycelia are sold in various online shops, sometimes as streaked wooden dowels or loose in plastic bags. Mushroom growing sets with ready-made substrate can of course also be fed with coffee grounds.

Many different offers for your own mushroom cultivation are 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 package has been sending various types of mushrooms from Nuremberg for a number of years, including as brood for growing on coffee grounds. In addition, the mycelia can be purchased locally in the city.

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

Mushroom males from Saxony sends certified organic mushroom substrates - also especially for growing on coffee grounds. Growing kits are now also available in the Dehner garden center.

Grow edible mushrooms yourself

If you feel like trying yourself out as a mushroom grower, you should be informed about the following aspects.

Which types are suitable?

There are many different types of fungus, 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, pressed-down hats that are rolled up at the edges when young. They are available in the colors pigeon blue, gray, 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

Lime oyster mushrooms / lemon yellow oyster mushrooms (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 reminiscent of lemon, which makes it very interesting as a side dish to fish or salads.

'Rose oyster mushroom' (Pleurotus djamor): Also called flamingo mushroom because of its pale pink color. The mushroom is related to the oyster mushrooms and has a fan-like, lamellar-coated fruit body with a velvety surface and a fine mushroom taste. Versatile in use.

'Shiitake' (Lentinula edodes): A fawn edible mushroom with light flakes on the round hat and light brown-whitish stem, which is very popular in Asian cuisine due to its umami taste. Suitable for all kinds of dishes.

'Pioppino' / 'Südlicher 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 meat 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 good in a mini greenhouse. Direct sunlight should be avoided, as should drying out the substrate. Mushrooms do need some light, but for them to grow properly it only needs to be moderately bright. If the substrate is by the window, care must be taken that there are no drafts, because the mushrooms cannot tolerate that at all.

Inoculating and caring for the mycelium

At the beginning, dry substrate must be soaked in water overnight so that the mycelium is stimulated to grow. Inoculated wooden dowels are usually damp enough and can be inserted directly into the coffee grounds. The moist substrate is now mixed with coffee grounds in a bowl. The ratio should be around 8: 2 coffee grounds to seed substrate. In addition, fine wood chips or straw loosen the mixture and ensure a balanced water balance. The mixture is now poured into a flower pot, a bag or a large glass and only lightly covered so that air can still get into it. Alternatively, you can drill holes in the lid or perforate 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 you always have to ensure that there is sufficient moisture and, if necessary, simply add some cold tap water. Waterlogging must be avoided at all costs, otherwise the mycelium can die. Now you should be patient, because after a further 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 room to grow out.

Harvest mushrooms

As soon as the first mushrooms appear, you can think of the harvest. In some species, such as the mushrooms, the downward-curved edge slowly unrolls with increasing size and then tears. Now is the perfect time to remove the mushrooms either with a sharp knife or simply by hand with a slight twisting motion. Harvest must be carried out at the latest when the spores of the fruiting bodies have fallen out and are visible as a brownish-grayish coating under the caps. Because now the fungus has served its purpose and dies within a short time.

If all fruit bodies have been harvested, the substrate should be allowed to soak itself properly with water. After a while, it will come to fruition again. After about one or two harvest waves, depending on the quantity, the nutrients in the coffee grounds are largely used up and need 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 can also easily multiply and pass them on.

Use of fresh mushrooms

The freshest mushrooms you can get unfortunately don't last very long and should therefore be stored in the refrigerator and consumed within three days. Of course, you can freeze, dry or pickle your own harvest in order to enjoy it longer. However, the taste is best when the extraordinary plants go straight to the saucepan. Edible mushrooms can, however, also be consumed raw and thus ensure a unique taste experience.

How you can grow mushrooms as an alternative on tree trunks, you can find out here in our special article.