Mushroom Evolution: Nature's Magic

Mushrooms are the fleshy, spore-bearing fruiting bodies of fungi, which are unique organisms that are neither plants nor animals. They are grown in a variety of ways, including on logs or in bags, beds, or trays filled with sterilized sawdust and compost. The ideal growing conditions for mushrooms are around 70 degrees Fahrenheit and greater than 90% humidity. The process of growing mushrooms involves seven main steps: strain selection, substrate preparation, inoculation, incubation, initiation, fruiting, and harvest. The substrate, or growing medium, is a key ingredient in mushroom production and can be made from synthetic or manure-based compost.

Mushrooms are fungi, not plants or animals

Mushrooms are fungi, which are unique organisms that are neither plants nor animals. They are a kingdom all their own. While fungi, plants, and animals are all eukaryotic organisms, meaning they are made up of cells whose DNA is contained in a nucleus bound by a membrane, fungi differ from plants and animals in some distinct ways.

Fungi do not photosynthesize like plants, so they cannot produce their own food. Instead, they are heterotrophs, meaning they obtain nutrients from other organic material, often other organisms. While animals also share this trait, they ingest and then digest their food. Fungi, on the other hand, secrete digestive enzymes into their environment and then absorb the nutrients released. The cell walls of fungi contain chitin, a strong but flexible compound also found in the exoskeletons of arthropods like beetles and crabs. This is why cooking mushrooms is essential!

Fungi also differ from plants in their reproductive methods. While all flowering plants grow from seeds, mushrooms grow from either spores or tissue culture. Every mushroom releases thousands of spores into its environment, each carrying unique genetics. Growing mushrooms from spores is unpredictable, and none will be identical to its "parent."

The first mention of mushroom cultivation was in 1652, when they were described as excellent for "making into compresses for ripening boils" but not for eating. In 1707, a French botanist wrote about mushrooms as "originating from a horse." The first record of year-round commercial mushroom production was in 1780. After the Civil War, gardeners introduced mushroom growing to North America by using dark areas underneath greenhouse benches. Shiitake mushrooms, in particular, have been enjoyed for centuries in Asia for their health-promoting properties and are now gaining popularity in Western countries for their unique culinary characteristics.

Ideal growing conditions: 70°F and 90% humidity

Mushrooms require specific conditions to grow successfully. They thrive in cool, dark, and humid environments with a temperature range of 55°F to 70°F (some sources give a broader range of up to 75°F). Maintaining this ideal temperature range is crucial as it prevents extreme temperatures from hindering growth.

At 70°F and 90% humidity, you're at the upper limits of the ideal temperature and humidity ranges for growing mushrooms. This is a sweet spot for many varieties. However, it's important to note that some mushroom species have different requirements. For example, Oyster mushrooms prefer a cooler temperature range of 55-65°F, while Shiitake mushrooms favour slightly warmer conditions of 50-60°F.

To maintain the ideal humidity level, you can use various methods, including misting spray bottles, pond misters, fans, perlite, and companion planting. One of the simplest and most cost-effective ways is to use a misting spray bottle, spraying the mushrooms and the surrounding area with water to increase humidity. This can be done multiple times a day to maintain the desired level. Additionally, creating a "humidity bell" with a transparent container or plastic tent can help maintain high humidity around the mushrooms.

It's also important to ensure proper ventilation to prevent mould growth and maintain adequate airflow. This helps regulate carbon dioxide levels, which, if too high, can negatively affect mushroom growth. Stagnant air can lead to poor mushroom formation and increase the risk of contamination.

Mushrooms grow from spores or tissue culture

Mushrooms are fungi, a unique kingdom of organisms that are neither plants nor animals. They do not photosynthesize like plants, so they cannot produce their own food. Instead, they are heterotrophs, obtaining nutrients from other organic material, often other organisms.

The most common method for growing mushrooms is inside large plastic bags filled with sterilized sawdust and wood chips. This method replicates natural conditions but leaves behind a lot of plastic waste. Another method is log growing, which has been used for hundreds, if not thousands, of years. Logs provide a growing medium that is naturally sterile and, when responsibly sourced, is sustainable and self-replenishing.

To grow mushrooms, a grower prepares a basic growing medium called a substrate. Two types of starting material are generally used for mushroom substrate: synthetic compost consisting of wheat or rye straw, hay, crushed corn cobs, cottonseed meal, cocoa shells, and gypsum, or manure-based compost made from stable bedding from horse stables or poultry litter. This process converts plant and animal products into decayed organic matter necessary for growing mushrooms. The substrate is then placed in stacked wooden trays or beds, and spawn is mixed in with a top layer of peat moss. From this point, it takes about three weeks to produce the first mushrooms for harvest.

Common substrates: synthetic or manure-based compost

Mushrooms are fungi, and their growth requires different conditions and equipment than plants. The ideal growing conditions for mushrooms are around 70 degrees Fahrenheit and greater than 90% humidity. The most common method for growing mushrooms is inside large plastic bags filled with sterilized sawdust and wood chips. Logs are another popular medium for growing mushrooms, as they provide a growing medium that is naturally sterile and, when responsibly sourced, is also sustainable and self-replenishing.

The basic growing medium for mushroom production is called a substrate. Two types of starting materials are generally used for mushroom substrates: synthetic compost or manure-based compost. Synthetic compost consists of wheat or rye straw, hay, crushed corn cobs, cottonseed meal, cocoa shells, and gypsum. This synthetic compost is a mixture of decayed organic matter that is necessary for growing mushrooms. Manure-based compost is made from stable bedding from horse stables or poultry litter. This process also converts plant and animal products into a mixture of decayed organic matter necessary for mushroom growth.

The substrate is placed in stacked wooden trays or beds, and spawn is mixed in with a top layer of peat moss. The temperature and humidity are carefully controlled throughout the growing period. Mushrooms mature at varying times, so they are picked by hand continuously for two to three weeks. The trays or beds are then emptied, and the growing area is pasteurized with steam before a new crop is started.

Specialty mushrooms like Shiitake, Oyster, and Maiitake are grown differently than common white and brown button mushrooms. They are often grown on logs or in bags. The process of inoculating logs requires mycelium (spawn) to be placed inside the growing medium.

Harvesting: by hand, continuous for 2-3 weeks

Harvesting Mushrooms by Hand

Harvesting mushrooms is a delicate process that requires care and attention. It is a continuous process that takes place over 2-3 weeks, as mushrooms mature at different times. Here are some key steps and considerations for successful hand-picking:

Step 1: Timing is Critical

Mushrooms take about three weeks to develop from the pasteurized substrate to the point of the first harvest. During this time, temperature and humidity are carefully controlled to create optimal conditions. The ideal temperature is around 70 degrees Fahrenheit, and humidity should be maintained above 85% in the initial stages, later dropping to 60-80%.

Step 2: Identify Maturity

Mushrooms mature at different rates, so it's important to monitor their growth closely. Experienced growers like Jeremy and Aimee from Northwood Mushrooms have a keen eye for identifying when mushrooms are ready for picking.

Step 3: Picking Technique

Every mushroom is harvested by hand. The picking technique varies depending on the type of mushroom and the growing medium. For example, shiitake mushrooms grown on logs will require a different approach than those grown in traditional beds or trays.

Step 4: Sterility and Cleanliness

While sterility is not as critical during the harvesting phase as it is during inoculation, maintaining clean conditions is still important. This helps prevent contamination and ensures the mushrooms are safe for consumption.

Step 5: Post-Harvest Processing

Immediately after harvest, mushrooms are sent to a packinghouse. Here, they undergo sorting, weighing, packing, and shipping to reach consumers.

Harvesting mushrooms by hand is a meticulous process that requires knowledge, skill, and attention to detail. Growers must be adept at recognizing the right moment to pick each mushroom to ensure a successful and bountiful harvest.

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