How to Grow Agaricus Bisporus

Obtain an Agaricus bisporus mushroom kit from a seed company, which includes the Agaricus spawn. The spawn is a mixture of Agaricus bisporus spores and organic material such as plant stems, grain and manure.

Ferment fresh compost at 140 degrees until the ammonia smell disappears, usually four to six days. The commercial method of accomplishing this is to manage a large compost pile to achieve the correct temperature. Private gardeners typically fill containers at least 3 inches deep with compost and heat them in ovens for the required period of time.

Move the compost to a well-ventilated room where you can control the temperature. This room is commonly known as the spawning room.

Plant the Agaricus bisporus spawn on the fermented compost according to the instructions in the mushroom kit. This generally means spreading powdered spawn on top of the compost or planting solid spawn into the compost.

Maintain the temperature in the spawning room between 75 and 80 degrees Fahrenheit. Wait for the mushroom spawn to grow through the top 3 inches of the compost in two to three weeks.

Spread a 1-inch layer of loamy soil over the compost bed. This casing soil helps the compost retain gases, so it should be not be overly sandy.

Maintain a temperature between 50 and 62 degrees Fahrenheit in the spawning room and keep the compost moist. The first mushrooms should sprout in three to four weeks.

Harvest the mushrooms as they reach a diameter between 1 and 2 inches. The harvesting period should last between six and seven weeks.