Notes: Growing Mushrooms on coffee ground [EN]

These are the expanded notes of a workshop I was participating a while ago.  You can maybe find some useful information in here, it’s a sort of a very resumed article that explain a method for cultivating mushrooms on your own at home + some background information. More than a guide, is an overview over the method. Enjoy!

Mushrooms Workshop


Mushrooms that grows in the nature are mainly decomposing the matter. They are at the base of life: they break materials like lignine, cellulose and minerals and split complex elements into smaller chemical substances that are beneficial not only for the organism itself, but also more easily absorbed from the organisms in the surrounding environment. What we call “mushroom”, is just the visible part of a very extended system of “roots” (hyphae) called mycelium, which is the actual organism.

The first production in the world is the so called «champignon» (agaricus bisporus) and the second one is the oyster mushroom (pleurotus ostreatus). These are quite easy to grow, that’s why the industry produce them on a large scale, but every mushroom can be grown, at the right.

What we do when “cloning” a mushroom, is to take a piece from the inside of a forest mushroom (or a cultivated one) and provide it with perfect conditions, so that the mycelium still contained in it can reproduce itself, until is so extended that can create the carpophore (mushroom) that we all like. The mushrooms, in fact, are just the ”fruiting bodies” over which the spores are produced and released (in order for the organism to spread around and reproduce). Spores are some sort of “seeds” of the mycelium. To achieve the reproduction, we’ll transfer the mycelium in different substrates, to help it having all the nutrients to develop. So the process we have to follow is: going in the nature, take an edible mushroom and reproduce the mycelium of it.

Pleorotus Ostreatus

The «saprophyte» mycelium – like Pleorotus Ostreatus –  like to eat dead material that contains a lot of lignine and cellulose, like decaying wood in forests, and for DIY indoor or outdoor production we try to reproduce these conditions. We can use different materials as substrate, like spent coffee ground, straw, sawdust or hay, or inoculate the mycelium directly on logs. Of course, the final substrate that you’ll use will depend on the type of mycelium you want to reproduce. It’s possible to add a little quantity of gypsum, carton, paper or newspaper, of course without to much ink or glue. The more natural is the substrate you’ll use, the better will be the results.

The coffee we take from an espresso coffee-maker or caffettiera has a good amount of water inside (moisture), as water has to pass trough it. For infusion-like coffee, you’ll want to filter it, letting water out and maybe add a few pieces of dry cardboard to absorb the excess water. If you recycled the coffee ground from your own daily coffee, you want to keep it in the fridge, otherwise mould will appear. When you squeeze the final substrate into your hand, a few drops of water can go out between the fingers, but no more.

The following guide is just for experiment purpose, to understand how to work with mycelium, and to enjoy to see it growing. If you want to have a big production, you will probably use a longer process. Anyway, the idea at the base of it, is to put a piece of mushroom inside a jar with sterilized substrate in it, and all in a clean environment.


All the process needs quite a good rate of cleaning and disinfecting of the environment, especially the earlier steps (the stronger gets the mycelium, the less likely will get infected later on). Clean and disinfect your working environment with alcohol:

– the table: don’t use a wooden one, metal or plastic are easier to clean;
– the tools you use (plates, knife or cutter): you can even flame-sterilize them with a alcohol burner;
– your hands: very important, you can use an alcohol spray for hands or use plastic gloves;
– the containers you’ll use to host liquid cultures, spawn (grains) and substrates (petri dish, jars, plastic box, bags or bottles) in case you cannot boil them, or sterilize them.
– if you can, even the walls and floor, and if they are tiled it’s even better;
– cover your hair (a clean T-shirt is ok) and beard if you have, put a mask (for the breath), put on clean clothes, long sleeve t-shirt and ideally take a shower before!

If you start from spores – that would be the step 0, but instead of putting a piece of mushroom, you would scratch with a scalpel the “spore-print” of it – it’s better to be in laboratory conditions here, possibly using a ventilator with HEPA filter (it filters 99,9% of bacteria). Some uses a plastic box with two holes for the hands to work in an environment that recreate these conditions.

It is necessary to take these precaution to avoid contamination from other moulds.

Practical Part

-1) Prepare the jar: do a hole in the lid with a screwdriver (2-3mm), and fit some poly-fill (I use a cigarette filter instead) through it. Seal all around the air-filter, top and bottom, with white silicon. This air-filter will allow air exchange with the outside of the jar, but limiting contaminants to go inside. At the same time, it creates a low-oxygen environment inside the jar, beneficial for the mycelium to grow.

0) Take one small piece from inside the stem of a fresh, possibly young mushroom (outside parts can contain other spores, bacterias, germs that can damage our process). Put this piece in a petri dish or otherwise small jar with a Potato Dextrose Agar (PDA) solution in it, that you previously sterilized by boiling and cooled down at room temperature. This passage is used to give a very strong starter to the mycelium.

1) Put cereals grain (barley, wheat, rye and many more) under water for 12 hours. Then, soak the water out and close them in the jar with air-filter. Boil the jar, water at 2/3 of it with small flame from 40 up to 90 minutes. Cool down at room temperature, then put a piece of the inside of a mushroom (or PDA fully colonized, if you made step 0) inside it, leaving the jar open just for a few seconds (you don’t want contaminants to enter it).

2) After around 2 weeks, the jar will be fully colonized by the mycelium (white fluffy substance growing all over) and you can prepare another jar in the same way as described above, or you can use plastic bottle or plastic bag cleaned with alcohol, but with your final substrate on it (coffee ground, straw, sawdust). A few spoons are enough to colonize one jar or one bottle, four spoons for a plastic bag, ecc.

As an experiment, you can also skip pass 0, putting directly a little part of a mushroom in grains or coffee, but that will probably be less productive.

3) Put the final jar or plastic bag to fructification! To achieve this, you need some source of light (window or bulb), less temperature (basement), more oxygen (you’ll open the jar) and more moisture (you’ll spray twice a day with water that you previously boiled and cool down at room temperature). You can use a plastic transparent box as fructification chamber, this will help moisture to be maintained and contaminants to be kept out.

Now you can start the production! The mycelium can stay alive more than a year in the closed jars, but it’s advised to put it to fructification as soon as it’s fully colonized. In order for the mycelium to start producing mushroom, you’ll need to “stress” it out, so you’ll change the characteristics of the environment (light, oxygen, temperature, moisture).

In facts, the two processes (colonization of mycelium and mushrooms production) needs different conditions. To give an idea:


low-oxygen rate (jars are closed, with air filter)
humidity at around 60%-70%


high-oxygen rate (jars are open)
80-90% humidity

Other possibilities

– liquid culture: you can make it (from step 0) or buy it on internet. With a very little amount, you colonize a lot of material.

– with liquid culture you can inoculate moisted wooden bits inside jars and when colonized, insert them in a wood log outdoor by drilling holes on it. Check the compatibility between the mycelium and the species of the tree you want to colonize. Close the holes with natural wax. Depending on how big is the trunk, it can take 6 month to 3 years to fully colonize, but then it will produce mushrooms during 6 to 9 years.

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