The short answer is that mushrooms generally do grow back after they are picked because the visible part is not the entire organism. Foraging or harvesting only removes the reproductive structure, similar to picking an apple from a tree. The main body of the fungus remains hidden beneath the soil, wood, or other material, ready to produce more mushrooms when conditions allow.
The Biological Answer: Mycelium vs. Fruiting Body
The mushroom that appears above ground is scientifically known as the fruiting body, and its sole biological purpose is to produce and disperse spores for reproduction. This structure is temporary and represents only a small fraction of the total fungus. The vast, living organism exists as an expansive, thread-like network called the mycelium, which permeates the substrate, such as soil or decaying wood.
The mycelium functions much like the roots and trunk of a tree, absorbing water and nutrients from its environment to fuel the entire organism. This network is composed of individual microscopic filaments called hyphae, which collectively form a dense, often invisible mat. When a mushroom is picked, the mycelium remains completely intact underground. The removal of the fruiting body simply signals the organism to initiate the growth of new mushrooms when resources and environmental cues are sufficient.
Environmental Factors Influencing Regrowth
Regrowth is not automatic, but depends on the mycelium receiving the correct environmental signals to trigger a new fruiting phase. The most significant factor is moisture, requiring high relative humidity, often 85% to 95%, to support the water-intensive process of mushroom formation. A lack of moisture will prevent the development of new fruiting bodies, even if the mycelium is otherwise healthy.
Temperature is another defining trigger, as many species require a temperature drop to initiate the formation of pinheads. These specific temperature shifts often signal the optimal season for spore dispersal, such as the cooling temperatures of autumn. Additionally, the health and nutrient content of the substrate must be maintained. As the mycelium produces successive “flushes” of mushrooms, it uses up the available carbon and nitrogen sources, and depleted substrate will eventually cause fruiting to cease regardless of ideal weather conditions.
Does Harvesting Method Affect Future Crops?
The method used to harvest a mushroom—cutting the stem with a knife versus twisting and plucking the whole body—has been a long-standing point of discussion among foragers. Scientific research suggests that the choice of harvesting method has a minimal impact on the long-term yield of the fungal patch. A multi-decade study found that systematically harvesting mushrooms either by cutting or pulling did not reduce the future fruit body yields or the species richness of the area.
The slight theoretical risk associated with cutting involves leaving a small, decaying stem stump, which could potentially attract pests or introduce pathogens to the mycelial mat. Conversely, twisting and pulling the entire mushroom risks mechanically disturbing the sensitive surface layer of the mycelium and the surrounding soil. In practice, however, neither technique has been shown to cause significant damage that would prevent future harvests. The most damaging factor is generally not the method of removal, but the trampling of the forest floor, which physically compacts the substrate and can reduce the number of future fruit bodies.