The classic terrarium is a glass enclosure, most often an aquarium, with or without a lid that contains a self-sustaining ecosystem requiring little or no human intervention. Terrariums are used as miniature, indoor greenhouses to grow low-maintenance gardens for decorative display. With lidded terrariums, the environment remains consistently humid making an ideal atmosphere for growing mushrooms. However, unlike classic terrariums, mushroom terrariums are not intended for display. Mushroom terrariums are constructed out of opaque materials and stored in a dark room to provide an ideal environment for mushroom growth. Different types of mushrooms require different growing mediums and environments so always follow specific growing instructions for your chosen crop.
Purchase mushroom spawn. Mushrooms grow from mycelium, the root system of fungi, not seeds. Mushroom spawn are composed of sawdust or another growing medium held tightly together by the mycelium. The spawn can be broken up into several pieces or left whole depending on the size of your terrarium and any growing instructions that might come with the spawn.
Obtain appropriate growing medium. The correct growing medium depends on the type of mushroom you will be growing in the terrarium. For example, shitake mushrooms prefer hardwood sawdust or logs, and white button mushrooms prefer composted manure.
Place the growing medium in the bottom of a 5-gallon bucket that has a lid.
Set the mushroom spawn in the growing medium. Use a spray bottle to mist the mushroom spawn and growing medium with water.
Place the lid on the bucket, but do not seal tightly. Some air must be allowed into the bucket. If a lid is not available, use a black plastic trash bag to cover the top of the bucket. This will block out light and keep in the humidity.
Locate a cool, dark place for the bucket to reside. Read the instructions for your chosen mushroom spawn very carefully. Some mushrooms require room temperature to fruit, while others require temperatures below 10 degrees C.
Monitor the mushroom terrarium, spraying with water to maintain a consistent humidity level. Depending on the type of mushroom, fruiting bodies will begin to appear in three weeks to six months.