Cultivating Psilocybe cubensis: Suitable Substrates

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

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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.

Summary

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
12 days 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.