How Mushrooms Grow
Mushrooms grow from spores -- not seeds -- that are so tiny you can't see individual spores with the naked eye. Because the spores don't contain chlorophyll to begin germinating (as seeds do), they rely on substances such as sawdust, grain, wooden plugs, straw, wood chips, or liquid for nourishment. A blend of the spores and these nutrients is called spawn. Spawn performs a bit like the starter needed to make sourdough bread. The spawn supports the growth of mushrooms' tiny, white, threadlike roots, called mycelium. The mycelium grows first, before anything that resembles a mushroom pushes through the growing medium.The spawn itself could grow mushrooms, but you'll get a lot better mushroom harvest when the spawn is applied to a substrate, or growing medium. Depending on the mushroom type, the substrate might be straw, cardboard, logs, wood chips, or compost with a blend of materials such as straw, corncobs, cotton and cocoa seed hulls, gypsum, and nitrogen supplements.
Where to Grow Mushrooms
Mushrooms prefer dark, cool, moist, and humid growing environments. In a house, a basement is often ideal, but a spot under the sink may be all you need. Test the proposed location by checking the temperature. Most mushrooms grow best in temperatures between 55 and 60 degrees F, away from drying, direct heat and drafts. Enoki mushrooms prefer cooler temperatures, about 45 degrees F. Many basements are too warm in summer to grow mushrooms, so you might consider growing mushrooms as a winter project. Mushrooms can tolerate some light, but the spot you choose should stay relatively dark or in low light. Some mushroom types grow outdoors in prepared ground or logs, a process that takes much longer (six months to three years) than in controlled environments inside.
Types of Mushrooms to Grow
There are many kinds of mushrooms. One of the beauties of growing your own instead of wild-harvesting them is that you can be sure you're not picking a poisonous mushroom. These mushrooms are the types most commonly grown at home:
- White button
Each type has specific growing needs. Grow white button mushrooms on composted manure, shiitakes on wood or hardwood sawdust, and oyster mushrooms on straw, for example.
If you are growing mushrooms in your home, you have a couple of options for materials. You can buy mushroom kits already packed with a growing medium that's inoculated with mushroom spawn. Buying a kit is a good way to begin your knowledge of mushroom growing. If you start without a kit, the type of mushroom you choose to grow determines the substrate you grow the mushrooms on. Research each mushroom's needs. Button mushrooms are among the easiest types to grow. Follow Kansas State University's directions for growing button mushrooms. Use 14x16-inch trays about 6 inches deep that resemble seed flats. Fill the trays with the mushroom compost material and inoculate with spawn. Use a heating pad to raise the soil temperature to about 70 degrees F for about three weeks or until you see the mycelium -- the tiny, threadlike roots. At this point, drop the temperature to 55 to 60 degrees F. Cover the spawn with an inch or so of potting soil. Keep the soil moist by spritzing it with water and covering it with a damp cloth that you can spritz with water as it dries. Button mushrooms should appear within three to four weeks. Harvest them when the caps open and the stalk can be cut with a sharp knife from the stem. Avoid pulling up the mushrooms, or you risk damage to surrounding fungi that are still developing. Harvesting every day should result in a continuous crop for about six months.