Mushroom Biological Cycle and Growing Requirements

A typical mushroom biological cycle has three main stages:

Vegetative growth → Starts with the production of primary or secondary mycelium from a (or 2) spore(s). The mycelium continues to grow mature.
Reproductive stage → It is initiated by external stimuli and starts with the formation of the pinhead and primordium and ends with the production of fruiting bodies (mushrooms)
Spores production (Sporulation) → The mature fruiting bodies sporulate.

To manage fungi that will produce mushrooms, it is essential to help them by providing them with optimum growing conditions. Different mushroom species have different requirements. However, they need controlled temperature, humidity, and good aeration (O₂ supply). Some species, like Pleurotus, also need light to grow, while others, like Agaricus, do not. In general, mushrooms need high humidity levels (over 80%) and temperatures between 10-20°C (50-68 °F ) to grow and enter the reproduction phase. Even if the light is necessary for the species' fruiting, many growers keep their bags (with the substrate and inoculum) in complete darkness during the mycelium stage. Later, during their reproductive phase, they are supplied with low-intensity light (close to 120 lux) to promote fruiting. If they remain in the dark, with the temperature close to 20°C for longer, they will continue their vegetative growth and consume all available substrate nutrients without producing any mushrooms. To enter the reproductive phase quickly, farmers reduce the temperature or increase the humidity levels (e.g., by watering). Additionally, throughout the whole lifecycle of the mushrooms, it is crucial to have good airflow, so oxygen must be renewed. Mushrooms produce large amounts of CO₂, which can cause serious problems for people and mushrooms if not removed from the growing room. Large commercial mushroom farms control the conditions via modern technological instruments. In small-scale farms, growers may rinse the floor to increase humidity, use fans and heaters to maintain temperature, and open the windows for proper aeration.

How to select a mushroom species and strain

There are nearly 35 species of mushrooms that can be cultivated commercially. To decide which species to grow, the farmer should consider the market demand, the availability and type of facilities and equipment, and the type of end product (dried, canned, or fresh mushrooms). After selecting one or more species to focus on, the farmer should be aware that there is a large variation among the different strains of a mushroom variety. It is important to mention that the selection of a strain is crucial since it can affect the growth rhythm of the mycelium, the environmental requirements (temperature) needed for fruiting, the color of the fruiting body, the resistance to diseases, the yield, and the post-harvest lifespan of the mushroom. Both small and large-scale farmers should experiment to find the best strain (combination).