How Do Mushrooms Grow?

 

Mushrooms are often mistakenly referred to as vegetables - plants from the kingdom plantae. They actually hail from the biological kingdom fungi, and are the fruit of a fungus called mycelium. They grow on the ground, the bark of trees and on decaying logs, all of which serve as a food source for the fungus.

92% of a mushroom is made up of water. Mushrooms can grow virtually anywhere, given ample moisture and protection from sunlight. As a general rule they are a cold-hardy fungus that prefers cool, damp regions.

Most mature mushrooms have four main components: The cap, the stem, the veil, and the gills. The veil is a thin layer that grows beneath the cap. As the mushroom matures, it peels away to reveal the gills, where the mushroom’s reproductive system lies. The mushroom’s gills release microscopic spores from which the mycelium grows and produces the fruit known as the mushroom.

There are over 140,000 known species of mushroom in the world and more are discovered every year. Over 100 varieties are estimated to be toxic to humans, and a few others produce hallucinogenic effects.

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Seasonal Growth

 

Health Benefits

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Of the more than 140,000 known species of mushrooms in the world, modern science is familiar with the health benefits of only approximately 10% of those species.

Mushrooms are low in fat, cholesterol, sodium and calories. Although there are many varieties, most contain approximately the same amount of nutrients per serving.

Mushrooms - in particular, white mushrooms (including crimini, Portobello and button) - contain high levels of phytonutrients that work to regulate the activity of the body’s immune system by triggering white blood cells when activity is needed, and preventing them from becoming active when they should be inactive. Balanced activity in the body’s white blood cell system plays an important role in the prevention of arthritis, cancer, and cardiovascular disease.

Beta-glucan fibers found in the cell walls of mushrooms stimulate the immune system to fight cancer cells and prevent the formation of tumors.

Mushrooms also provide high levels of the mineral, selenium, as well as good levels of manganese and zinc. These three minerals are all important in the function of antioxidant enzymes.

Selenium, in particular, is a mineral that is not found in most fruits and vegetables, but is highly present in mushrooms. It is related to liver enzyme functioning, helps to detoxify cancer-causing properties in the body, is an anti-inflammatory agent and has been reported to decrease the rate of tumor growth.

Portobello and shiitake mushrooms are high in dietary fiber. One cup of either provides approximately three grams of fiber. Diabetics who consume high fiber diets have lower blood glucose levels. Increased consumption of mushrooms among type 2 diabetics may improve insulin, blood sugar and lipids levels.

Two types of dietary fiber, beta-glucan and chitin, assist in weight management by reducing appetite and increasing satiety, meaning they make you feel “fuller” longer. Dietary fiber helps to maintain healthy digestive processes.

 

History

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From ancient Egypt to the Aztec civilization, wild mushrooms have been a “fungus among us” for thousands of years, and were undoubtedly consumed by humans before the dawn of recorded history. Evidence of mushrooms is present in ancient Egypt, Greece, Rome, China, and throughout Latin America, as well as other cultures around the world.

 

In ancient Egypt, mushrooms were considered the food of royalty, only to be consumed by pharaohs. Ancient hieroglyphics dating back as far as 4600 BCE claim mushrooms to be the plant of immortality.

 

The Greek word for mushroom, mykes, is the root of the modern term for the study of mushrooms, mycology.

While wild mushrooms were on the menu throughout ancient history, their cultivation was not recorded until the first millennium in ancient Asia, sometime in the Middle Ages. In Europe, they made their appearance in 17th century France, with the first cultivation of white mushrooms. During this time, France became the leader in formal mushroom cultivation practices. eerily, they were grown in the catacombs of Paris, a tradition that lasted until the 20th century, when the city needed to make way for its metro system and moved its mushroom farms to caves outside the city.

The popularity of the mushroom spread from France to England. Although they were consumed among indigenous cultures in the Americas, their cultivation was not practiced by European colonists in the United States until the 19th century, when mushroom spawns were imported from England. Because the spawn were generally in poor condition by the time they traveled across the Atlantic, it was not until 1903, when USDA scientists produced the first pure-culture virgin spawn, that mushroom cultivation practices were refined in the United States.

 

Propagation

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Mushrooms require dark, damp environments to thrive, so most are grown indoors.

Rather than producing seeds, mushrooms have microscopic spores (up to 16 billion of them!) that are attached to the mushroom’s gills. Growers plant the spores in compost beds, and mycelium grows from them serving as the mushroom’s root system. Once the mycelium breaks the ground surface, mushrooms emerge and grow quickly, typically doubling in size overnight.

Rather than growing in the ground, some varieties of mushrooms attach to trees and decaying logs. In the wild, the rain and shade from overhead tree canopies keep these mushrooms moist and cool. In commercial settings, they are grown on fake logs made of sawdust and other plant material, which are drenched in water baths to ensure moist growing conditions.

Most varieties of mushroom produce fruits within 10 days of spawning. They continue to grow once harvested, and growers can harvest up to 3 times in a three-month period. Portabello, crimini and white button mushrooms fruit up to a week later but yield more mushrooms.

Shitakes can be harvested every 2 weeks in a three-month long growing season.

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Harvesting

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Mushrooms are ready to be harvested when the veil, which connects the cap and the stem, is lifted.

Mushrooms are harvested by holding them firmly and twisting them out, or cutting them off near the base of the stem. This method is applicable to mushrooms that grow on the ground, as well as those that grow on logs or tree trunks. Pulling the mushrooms directly out of the ground runs the risk of dislodging or damaging other mushrooms growing nearby that share a root system.

Mushrooms must be picked regularly providing an opportunity for the flush to continue to spread, ensuring a long and productive harvest.

Many varieties of mushroom don’t like the frost and get mushy, but others continue to grow well into winter. Boletus don’t like it, Agaricus are hard to find, but oysters start fruiting in response to a frost. Field and wood blewits also continue growing well past the first freeze.

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Storage

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As a general rule, when cleaning mushrooms, as little water as possible is used. This prevents them from losing their flavor. Clumps of dirt, leaves or other organic matter are first scraped away and bad portions cut off. A mushroom brush or a soft-bristled toothbrush removes finer soil particles. Finally, a damp cloth or a quick rinse are used to remove any remaining debris.

 

Fresh mushrooms can only be stored in the refrigerator for up to a few days at most by putting them in a plastic container and covering them with a damp towel to prevent them from drying out..

 

Mushrooms can be frozen whole by dropping them in a pot of boiling water for one minute to blanch. Then they are drained and put on a cookie sheet in the freezer for 40 minutes, or until frozen. They are then ready to be put in plastic bags and returned to the freezer.

 

Mushrooms can also be preserved by drying. Stems and other tough parts are removed, and the mushroom thinly sliced. Slices are placed on dehydrator racks or a cookie sheets lined with parchment paper. They are then heated in an oven set to 150 degrees Fahrenheit, with the door slightly cracked, until all moisture is removed. Dried mushrooms are stored in an airtight container in a cool, dark place or in the freezer if the moisture has not been completely removed.

 

Thoroughly dried mushrooms can be further preserved as a powder to use in soups and other recipes. A coffee grinder is used to grind them to a powder, and they are then stored in a well-sealed container in a cool, dry place. Powdered mushrooms have a very intense flavor.

 

Fun Facts

China, the United States, the Netherlands, Poland and France are the world’s top commercial producers of mushrooms (FAOSTAT, 2010).

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There are thousands of varieties of mushrooms in the world, and no shortage of edible varieties. Some of the most popular varieties of edible mushrooms include: white mushrooms (which include portobello, crimini, and button), chanterelle, oyster, shiitake, porcini, morel, and enoki mushrooms.

 

There are also over 100 varieties of mushrooms poisonous to humans. It’s important when picking mushrooms to be familiar with which ones are edible and which are toxic. Following is a chart of poisonous mushrooms and their effects when eaten:

Species

Toxicity

Effects

Alpha-amanitin

Deadly

Causes liver damage 1–3 days after ingestion. Principal toxin in genus Amanita

Phallotoxin 

Non-lethal

Causes gastrointestinal upset. Also found in poisonous Amanitas

Orellanine  

Deadly

Causes kidney failure within 3 weeks after ingestion. Principal toxin in genus Cortinarius

Muscarine

Potentially Deadly

Can cause respiratory failure. Found in genus Omphalotus

Gyromitrin

Deadly

Causes neurotoxicity, gastrointestinal upset, and destruction of blood cells. Principal toxin in genus Gyromitra

Coprine 

Non-lethal   

Causes illness when consumed with alcohol. Principal toxin in genus Coprinus

Ibotenic acid 

Potentially Deadly

Causes neurotoxicity. Principal toxin in Amanita muscaria, A. pantherina, and A. gemmata

Muscimol

Potentially Deadly 

Causes CNS depression and hallucinations. Principal toxin in Amanita muscaria, A. pantherina, and A. gemmata

Psilocybin and psilocin  

Non-lethal

Causes CNS arousal and hallucinations. Principal 'toxins' in psilocybin mushrooms, many of which belonging to the genus Psilocybe

Arabitol

Non-lethal

Causes gastrointestinal irritation in some people

Bolesatine

Non-lethal 

Causes gastrointestinal irritation, vomiting, nausea

Ergotamine

Deadly

Affects the vascular system and can lead to loss of limbs and death. An alkaloid found in genus Claviceps.

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Mushrooms are a highly versatile edible. Some varieties may be eaten raw, or they may be cooked in many ways. They are a common ingredient in soups, salads, pastas, casseroles, stir fries, side dishes, omelets, and even truffle oils and vodkas used to flavor gourmet dishes. Portobello mushrooms make an excellent meat substitute and are sometimes used to make vegetarian “portobello burgers.”

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Grow it yourself

Growing mushrooms at home is not as difficult as it may seem.

Pick a variety that you enjoy eating, as you will produce a large crop. Pre-inoculated mixes of mushroom “spawn” may be bought from nurseries.

Mushrooms require a cool, dark, moist environment, so most growers cultivate them indoors. A terrarium is a terrific environment for growing mushrooms. In lieu of a plastic terrarium, a styrofoam cooler, an old fish tank, or a plastic storage bin with a lid can be used.

Add a thin layer of growing medium to the bottom of the terrarium and sprinkle the spawn mix on top. Cover with approximately two more inches of growing medium. Mushrooms, unlike plants, do not produce their own nutrients, so a good medium must be provided that includes nitrogen, starches, cellulose and sugars. A basic mix should include nitrogen-rich compost or manure and wood chips or sawdust. 

Keep the chamber at around 70 degrees Fahrenheit. It will take approximately three weeks for the mycelium to spread roots through the medium.

Check for the thin, white, spider web-like formation of the root base. When this emerges, cover with one inch of regular potting soil, then cover the terrarium or place in a dark room, such as a basement, and reduce the temperature to 60 degrees Fahrenheit.

Spray the surface soil regularly with a water mister to maintain dampness. If the container is in a heated indoor space, spray daily.

Keep an eye on developing mushrooms over the course of the next 3 to 4 weeks. If mushrooms are slimy or have visible black dots, you will need to start over. Otherwise, mushrooms are ready to be picked when the veil (connecting the cap to the stem) is lifted. Cut carefully so as not to disturb mushrooms growing nearby.