Cultivating Psilocybe cubensis: Suitable Substrates

From cow dung to coffee grounds. this species grows well on a variety of substrates.


In a recent article, Psychedelic Science Review examined how light exposure and tryptamine levels play a part in the cultivation of the magic mushroom Psilocybe cubensis. In particular, the article discussed how both of these variables affect the psilocybin and psilocin concentrations in the mushroom. 

This article explores the versatile range of substrates suitable for P. cubensis cultivation. While the growing medium it enjoys is versatile, P. Cubensis only produces fruitbodies (mushrooms) under optimum conditions of temperature, humidity, nutrition and pH.1  

Outdoor Cultivation Substrates

According to psychedelic mushroom expert Paul Stamets, P. cubensis grows in tropical and subtropical climates, often in close connection with grazing cattle.2 With cow dung being the favoured habitat of P.cubensis, its circumtropical distribution is largely supported, if not caused, by the worldwide cattle ranching industry. The reason this species loves cow dung is that cows have minimal stomach acid, providing a welcoming environment for the fungus. The cow usually eats grains or grass, covered with mushroom spores. The spores then germinate in the cow’s moist, warm stomach.

In his paper titled The Outdoor Cultivation of Psilocybe cubensis, Gerald Peppard recommends aged cow dung as the prime natural substrate for the fungus.3 The moisture content should be the same consistency throughout the whole piece of dung, dry.

Indoor Cultivation Substrates 

Regarding indoor cultivations, mushrooms thrive on a multitude of substrates including coffee, brown rice flour, straw, and sawdust.4 The most suitable substrate for P.Cubensis is said to be rye grain. If grown inside a mason jar – a popular and effective method of cultivation – mycelium will permeate the grain within ten to fifteen days.

There are two approaches when growing mushrooms in a jar; either leave the container alone at room temperature or “case” it with soil. Jars left uncased ordinarily produce mushrooms within a month. There are usually only a few flushes (crops), as the grain dries out unless kept in a highly humid environment.

Casing Layer

Many cultivated mushroom species, P. cubensis included, will fruit abundantly if the substrate is coated in a soil-like layer known as a casing layer.4 Casing soils generally consist of non-nutritive materials with high water-holding capabilities, such as peat moss; or vermiculite, along with gypsum and calcium carbonate. The casing layer serves several vital functions for the developing mushrooms. 

Since a highly acidic environment can be damaging to the fungus and can promote the growth of bacteria, the addition of chalk (calcium carbonate) to casing soil serves to maintain a slightly basic environment (a pH between 7.5 and 8.5).1 Because of its high water content, the casing layer helps to keep the substrate from losing moisture to the atmosphere. This creates a humid microenvironment which acts as a water reserve for dehydrated mushrooms to draw upon as they grow. 

Since the casing layer takes up and releases water like a sponge, it also allows a grower to easily maintain a bed at its optimum moisture level while minimizing the risk of waterlogging the substrate and drowning the fungus.


Like many organisms in the natural world, there are several approaches one can take when cultivating P.cubensis. The fungus appears versatile and durable owing to its wide distribution around the globe. However, correct cultivation requires careful consideration of the substrate, pH of the environment, and other factors. 


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Andrew Chadeayne
1 year ago

Great article – very interesting – thanks for writing. That’s really cool how the spores germinate in the cow’s stomach so the dung comes out already inoculated and ready to go.

Doug Lundy
1 year ago

interesting how the content never fulfills the promise of the title, or even tries. The info here could be summarized, It Varies..C’mon. So substrates?? I will keep searching!

7 months ago
Reply to  Doug Lundy

Why Aren’t we cooking Cow Manure?…..It seems like a logical choice, v. Rice flour or rye. Anyone ever try it?

3 months ago
Reply to  Tom

I believe this is due to the unclean nature and risk of illness associated with cow manure.

2 months ago
Reply to  Tom

I wondered the same actually. I think the BRF cakes are terribly inefficient. That is just my opinion.

Yolo Grower
6 months ago
Reply to  Doug Lundy

There’s an entire paragraph that gives you substrate options and then the author even adds the bonus of a soil enclosure. Are we reading the same article???

9 months ago

I took the the article at face value. Its basic, much appreciated. Had ph questions as well as substrate ideas. Covered both. TY

Bryan Fender
8 months ago

I’ve been researching the magic mushroom for about a month. At first it appeared that this wonderful fungi was easy to grow. But, as I maneuver through the articles I’m starting to discover that it’s not as easy as it appears. I’ve looked at different methods. One item in common within each article is the fact that your growing area must stay CLEAN!!! Without cleanliness contamination can occur and your grow becomes worthless. Thank you for your article. Hopefully, us potential mushroom growers will find the magic pathway to successful growing.

7 months ago
Reply to  Bryan Fender

For smaller-scale personal growing, a clean/sterilized workspace isn’t as necessary as you think. If you’re inoculating pre-sterilized substrate jars then that’s the one time (at least in my experience) that you need to be very careful of contamination. Once the jars have been successfully colonized, the mycelium will has its own immune system and can fight off mold and bacteria to a point. Your fruiting chamber doesn’t need to be sterile. I wash it with soap and water between each grow. My general rules are to never touch anything with my bare hands and no bare hands in the fruiting… Read more »

2 months ago
Reply to  Bryan Fender

Speed is your friend in the beginning stages. I think using a good liquid culture is very helpful. It is super easy to make. Your jars can fully colonize in 9-10 days. Injecting with spores can take double the amount of time to fully colonize. During that time mycelium is vulnerable to attacks from competition/contamination. Keeping the temperature in ideal range is important also. The mycelium is vulnerable to competition when it is starting out. Once it has fully colonized your grain jars it is actually pretty tough.

30 days ago

This article seems sort of dated. It conflates grains and bulk substrates and casing layers — those terms have perhaps evolved over time. The most common way P. cubensis is cultivated indoors is as follows: (Germinate spores on agar plates) – Innoculate hydrated, sterilized grains with live mycelium or spores – Transfer colonized grains to a modified or unmodified plastic tub – Mix grain spawn with a bulk substrate in the tub, most commonly a low-nutrient substrate like pasteurized coco coir. Pasteurized straw or manure-based bulk substrates are also sometimes employed. High-nutrient substrates may possibly increase yield, but definitely increase… Read more »