Proper Storage of Mushroom Spawn

Production

• Commercial mushroom growers produce spawn in controlled environments. These environments encourage the production of healthy, uniform mushroom lines. Mycelium -- the thread-like components of mushroom anatomy - are used to inoculate sterile substrates. The substrate then becomes what is called "spawn." Slow-release nutrients are also added to this mixture and work to temporarily stall mushroom development until the spawn is planted in a suitable growing bed. Home growers do not have the equipment necessary to produce sterile, controlled mushroom spawn. Growing spawn from spores often results in mixed hybrid varieties that may not be suited for consumption. To ensure the production of a healthy, edible mushroom crop, home growers purchase spawn from reputable sources.

Techniques

• Spawn is stored for future growth within prepared substrates. Depending on the mushroom species and variety the substrate can be cereal grain, straw, hulls, or agar. The substrate is sterilized through pasteurization and steam heating and then placed within a growing container such as plastic bags, bottles or sterilized plates. Once inside the container the substrate is kept at a temperature within the 60-degree F. range. Mycelium strands, which are stored cryogenically within vials, are uniformly injected into the substrate, a process called inoculation. Here the mycelium and substrate mixture, the spawn, will remain in safe storage until it is heated and planted, thus triggering its growth.

Bags

• Spawn is sometimes stored and sold within specially designed plastic bags. These bags are constructed of polyethylene and allow for needed oxygen and carbon dioxide exchange. This exchange allows the mycelium to remain viable but does not allow it to grow. Growth is triggered when temperatures are bought up from the 60-degree range into the 70-degree range, setting the stage for an incubation period. Within a week or two mushrooms will begin to emerge from the bag ready for harvest and consumption.

Bottles

• Bottle containers are also used to store spawn. Sterilized bottles are filled with spawn and promptly covered with lids. The spawn will stay viable but unproductive until the lid is lifted and surface scratched. Once the spawn has been disturbed, and exposed to air, the spawn will begin mushroom production.

Trays

• Trays are another container/substrate growing medium that are available for purchase through nurseries and catalogues. Plates are similar to seed start trays. Once the home grower has prepared a mushroom growing bed, the spawn plugs, which are approximately 1-1/2 inches in diameter, are transferred to the permanent bed and spaced approximately 8 inches from one another. The plugs will begin to grow within approximately 20 days.