How to encourage mushroom growth in your garden
Each species of fungus relies on the availability of a certain substrate for the mycelium to digest before a mushroom can appear. Hence, in order to establish and maintain a mycological landscape, a continuous flow of organic debris is essential.
Each species that a cultivator may wish to introduce to a garden will have its own unique set of requirements in order to flourish. This will include a certain amount of light or darkness and humidity and temperature, specific to each species.
If we wish to succeed when introducing a species into a garden, we must look to nature for working examples. The key is in creating an environment wherein the planted mycelium naturally and vigorously expands. By incorporating several different species into a landscape, one is capable of harvesting several varieties of mushrooms throughout the year.
The first written record of mushroom cultivation dates back to the Sung Dynasty (A.D. 960 – 1127) and details the cutting of logs from fallen trees upon which Shiitake mushrooms were found. These logs were then submerged in streams to soak up as much water as possible. After the logs had attained high moisture content, they were removed and hit with rocks and large hammers. This shock treatment would stimulate the mushroom mycelium into fruiting and became known as the “Soak and Strike” method.
It was noted that by placing freshly cut logs near fruiting mushrooms the spores impregnated the logs and soon more mushrooms were produced. Some years later a technique was developed where pieces of bark were removed from freshly cut logs and live mycelium placed therein. The bark was secured back in place and the logs then stacked and placed in a position conducive to fungal growth.
Today, numerous methods of mushroom cultivation exist; from high tech sterile tissue culture, to simple techniques involving little or no technical expertise. The techniques we will discuss are: Spore-mass inoculation, transplantation, and inoculation with pure culture spawn.
Spore-mass inoculation
This is by far the easiest way to grow mushrooms and involves simply broadcasting spores onto a prepared substrate outdoors. First, spores of the desired species must be collected. When collecting spores, one must select a mature mushroom specimen that has been positively identified as the same species you wish to grow.
If you are not able to use the mushroom as soon as it has been found, take a spore print. To do this, cut the stem from the mushroom cap and place it, gills down, on top of a clean piece of typing paper, glass or similar surface. After 12 hours, most mushrooms will have released thousands of spores, which fall according to the radiating symmetry of the gills. After the spores have fallen, the print can be sealed and stored for future use and even be posted around the world without harm. These spores, if stored in a cool, dark and dry location can remain viable for many years. By collecting the spores of many different species and storing them together with information regarding the mushroom and its place of origin, you can create a species library! A mushroom hunter may encounter a certain species only once in a lifetime, and a properly taken spore print may be the only resource a cultivator has for future propagation.
If you are able to inoculate an area with a freshly found specimen, a more efficient method of spore collection is recommended. This method involves the immersion of the mushroom in water to create a spore-mass slurry.
In a 20 liter bucket of water place 1 gram of table salt, 50 milliliters of molasses and 1 mature mushroom of the desired species. Stir and leave covered with a cloth for 4 hours. After 4 hours most mushrooms will have released tens of thousands of spores into the liquid and may now be removed before stirring the liquid again. The salt acts to inhibit the growth of bacteria while the molasses stimulates the spores into a frenzied state of germination. Allow this broth to sit for 24 – 48 hours at a temperature above 10ºC but below 27ºC. During this stage the desired mushroom patch habitat should be constructed. After 48 hours the slurry can be diluted at a ratio of 1:10 and sprayed or watered onto your patch.
Transplantation
Transplantation is the moving of mycelium from naturally occurring places to new habitats. Early mushroom hunters who having returned home after gathering wild specimens for consumption have accidentally cultivated some species by throwing the stem buts and trimmings into their compost heap at home.
Most wild mushroom patches have a vast network of mycelium emanating from beneath the stem. Small pieces of mycelium often remain clinging to the base of the mushrooms stem and, if they are not allowed to dry out, they quickly re-grow. With this in mind one is able to transplant wild mushrooms that we encounter by carefully digging up the soil surrounding a mushroom and placing it in damp newspaper or cardboard. This soil must not be allowed to dry out and should be placed in a suitably prepared position as soon as possible. This method ensures the quick establishment of a new colony without having to germinate spores or buy commercial spawn.
Inoculating Outdoor Substrates with Pure Cultured Spawn
In the early history of mushroom cultivation, mycelium was collected from the wild and transplanted into new substrates. This later evolved to using colonised mushroom beds as spawn to inoculate more beds. In 1933 however, spawn technology was revolutionised by Sinden’s discovery of grain as a spawn carrier medium. After mushroom mycelium has colonised grain, each kernel of grain becomes encapsulated in a sheath of mycelium. Each individual grain now acts as a mushroom “seed”, with mycelium able to spread from each grain into a desired substrate.
The advantage of using commercial spawn is in acquiring mycelium of a higher purity than that which can be harvested from nature. Commercial spawn is available in two forms: Grain spawn and Sawdust spawn. When inoculating outdoor patches, sawdust is preferred to grain as the grain attracts insects, birds and slugs that quickly seek out the grain as food. Another advantage is the price difference between grain spawn and sawdust spawn. With sawdust spawn one is able to inoculate patches at a far higher inoculation rate than grain, which allows for rapid colonisation, increasing the chances of success tremendously.
Outdoor mushroom beds should be prepared as required. Leaving a prepared bed to sit for a month or two before use will lessen the likleyhood of your desired species being able to colonise the substrate due to the rapid occurrence of other weed fungi. Likewise, starting with old materials that undoubtedly already have a high content of mixed fungus spores will achieve a low success rate. If in the event mushrooms do emerge from these patches, you must be absolutely certain to identify each species before deeming it fit for consumption.
The best course to follow is starting with freshly harvested materials wherever possible. An excellent source of fresh materials are municipal garden refuse dump sites. Starter materials should be processed with a shredder to create a homogenous mixture of equal particle sizes. These can then be soaked in water overnight before utilising to ensure the optimum moisture content is attained.
Edible & Medicinal mushroom species that can be introduced to a garden
A) Gilled Mushrooms
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SPECIES |
DESCRIPTION |
CULTIVATION TYPE |
Stropharia rugguso annulata |
Commonly known as wine caps or king stropharia due to the wine red colouring of the caps when young and to the mammoth proportions they grow when left unpicked. They are very popular in Europe where they enjoy the reputation of being the most commonly cultivated outdoor mushroom. Gardens with beds of woodchips support abundant fruiting of this species. |
Garden Bed |
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Shiitake mushrooms are undoubtedly the most popular gourmet mushrooms worldwide; having numerous scientifically recognised medicinal properties. It has been cultivated on oak logs in China for at least 1000 years. |
Log |
Coprinus comatus |
Known as the Shaggy Ink Cap or Shaggy Mane. This easy to identify species is difficult to confuse with any other poisonus mushroom. It is frequently found in urban areas, open grassland, disturbed ground, rubbish dumps and roadsides. This mushroom is common in European mushroom markets, where it is regarded as one of the most savoury of all fungi. |
Garden Bed |
Agrocybe aegerita |
The Black Poplar Mushroom. This is a wood saprophyte commonly found growing prolifically on dead trees and stumps, but also on soil rich in woody debris. These mushrooms have a mellow attractive flavour, reminiscent of pork. Best eaten when they are young. This is an excellent species for inoculating stumps and beds of wood chips. |
Log or Stump |
Agaricus campestris |
The field mushroom. This universal species is often found growing in rings in richly manured meadows and pastures worldwide and is eaten throughout its range. It always occurs away from trees, from sea level to high mountains. Known since Greek and Roman times and even prescribed as medicine in some parts of the world. |
Garden Bed |
Agaricus bitorquis |
Commonly known as the pavement mushroom, being found growing almost exclusively in urban areas. Usually found singly and sometimes in dense clusters on hard packed soil, from cracks in pavements, in gutters and on old driveways. The flesh is rather tough but it is perfectly safe to eat and prized by those who have tried it. |
Garden Bed |
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Agaricus brunnescens (bisporus) |
This is the commonly cultivated button mushroom found in supermarket stores worldwide and encompasses both the white and brown varieties. In nature this mushroom is found growing on manure and on soil rich in organic matter. |
Garden Bed |
B) Polypore Mushrooms
Bracket Fungi with pores not gills, are the most medicinal of all mushroom species. Polypores are wood saprophytes that are traditionally boiled in water to make a tea with potent anti-fatiguing, immune enhancing and soothing properties. Polypores offer novel drugs with antiviral, antibacterial and tumorcidal properties. Through modern scientific research, polypores have been proven to cure cancer, heart disease, diabetes, arthritis, sexual impotency and HIV. The most highly regarded species of polypore are:
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