Fungiculture, or mushroom cultivation, is an intricate agricultural practice focused on growing fungi in highly controlled environments. Unlike traditional farming, mushrooms are the visible, spore-bearing reproductive structures (the fruiting body) of a larger organism, the mycelium, which lives beneath the surface. The mycelium derives its energy from decomposing organic matter within its growth medium. The entire cultivation process is a carefully managed sequence of phases, demanding precise control over temperature, humidity, and substrate composition.
Preparing the Substrate and Environment
The cultivation cycle begins with preparing the substrate, which serves as the food source for the fungus. This growth medium can consist of materials like agricultural byproducts, straw, wood chips, sawdust, or composted manure, depending on the mushroom species. Because the substrate is rich in nutrients, it must be treated to eliminate competing organisms, such as mold and bacteria, that could overwhelm the slower-growing mushroom mycelium.
Decontamination is achieved through either pasteurization or sterilization. Pasteurization involves heating the substrate to moderate temperatures (60°C to 80°C) for one to two hours. This method reduces unwanted microbes while leaving some beneficial microorganisms, which is common for oyster mushroom cultivation. Sterilization aims to eliminate all living organisms and spores by applying heat above 121°C (250°F) under pressure for several hours, a requirement for nutrient-dense substrates like grain or supplemented sawdust. The prepared substrate is then adjusted to a moisture content of 50% to 75% and placed in a container.
The Process of Inoculation and Colonization
The next step is inoculation: introducing the desired fungus into the prepared substrate. This is done using “spawn,” a carrier—often sterilized grain—that has already been fully colonized by the mushroom’s mycelium. The spawn acts as the starter culture, ensuring a vigorous and contaminant-free beginning.
The spawn is thoroughly mixed into the substrate, a process often called “through-spawning,” to distribute the mycelium evenly and speed up growth. Once mixed, the substrate enters the colonization phase (spawn run or incubation), which is a period of vegetative growth. During this time, the mycelium—a vast, root-like network of white, thread-like filaments—spreads throughout the substrate, consuming nutrients and binding the material into a solid block.
Colonization typically lasts between two and four weeks, depending on the species and conditions. The environment is maintained at a warmer temperature (24°C to 27°C) and kept dark, as the mycelium does not require light. While the mycelium requires oxygen, carbon dioxide levels are generally kept high during this stage to suppress the premature formation of the fruiting body.
Inducing Fruiting and Harvesting
Once the mycelium has fully colonized the substrate, forming a dense white mat, the environment is altered to trigger the reproductive phase, known as fruiting. This change simulates the shift in seasons that prompts the fungus to produce mushrooms. Primary triggers involve a drop in temperature, a significant increase in fresh air exchange (FAE), and exposure to indirect light.
The increase in fresh air exchange is important because it lowers the concentration of carbon dioxide produced by the mycelium during colonization. This drop in CO₂ signals to the fungus that it has reached the open air, prompting the formation of “pins” or primordia (the tiny, initial formations of the caps and stems). High humidity, often maintained above 85%, is necessary to prevent these pins from drying out as they develop.
Mushrooms are ready for harvest typically just before or as the cap fully opens and begins to drop spores. They are carefully removed from the substrate. Growers choose between cutting the mushroom at the base with a clean blade or twisting and gently pulling the entire structure out. Cutting leaves a small stump that can potentially rot, while twisting and pulling can slightly disturb the substrate. Both methods are used successfully to allow the substrate to recover and produce subsequent waves of mushrooms, known as flushes.