RICHMOND COUNTY — Mushrooms are the fruiting bodies of fungi and typically develop above whatever substrate the mushroom is growing in, whether soil, rotten logs or wood. Within the substrate, hyphae which act like roots, transporting nutrients. The hyphae form thread-like networks called mycelium. You may have seen mycelium under mulch or a decaying log. When conditions are right and a sufficient amount of mycelia has developed, fruiting occurs, resulting in mushrooms, which come in incredibly diverse shapes, sizes and colors.
Mushrooms have been cultivated since 7th-century China for both medicinal and culinary uses. Although millions of fungi species exist, only a little more than 10,000 have been identified and named. Among those, there are a small number commonly grown for food. Popular species include shiitake, oyster, lions mane, wine cap, almond agaricus, and nameko. Shiitake are one of the oldest agricultural crops and are the most reliable fruiting of the outdoor grown mushrooms.
The most common methods of growing mushrooms outdoors are on logs, totems, and in beds. All require spawn, which is mushroom mycelium that is grown in sterilized grains, sawdust, or hardwood plugs. For mushroom production, spawn is typically sourced from specialty producers, of which there are a number found online. In addition to spawn, a substrate or something for the mycelium to grow in is needed. Introducing spawn to the substrate is called inoculation. Each mushroom species has a preferred method and substrate they prefer to grow on. For example, shiitake grow very well on logs from oak, sugar maple, beech, birch, chestnut, and sweet gum; wine caps grow on beds of hardwoods chips; and oyster grow on both bolts and totems from poplar, willow, and box elder.
Growing on logs
Shiitake, oyster, and nameko mushrooms grow well on logs. Fresh wood is essential. Logs should be inoculated within a week or two of cutting. This prevents contamination of the logs by undesirable naturally occurring fungi. Logs should be 4 to 6 inches in diameter and 3 to 4 feet long. To inoculate, drill 12mm diameter holes 1 inch deep and 4 inches apart. Create rows of holes around the length of the log, 2 inches apart, staggering the holes to create a diamond pattern. Holes are filled with sawdust spawn using an inoculation tool or spawn plugs that are hammered in. The inoculated holes and log ends are then sealed with wax to prevent the log from drying out. Logs should be placed in shade and watered during dry periods. Depending on the size of the logs, they typically fruit after about a year and can produce for several seasons.
Growing on totems
Oyster and lions mane are grown on freshly cut logs stacked end to end to create a totem type stack. Eight to 12 inch diameter logs are cut into 1 foot lengths and stacked on their ends up to 3 sections tall; top the stack with a cut 2” thick log of similar diameter. To inoculate, place a layer of spawn between each section. Mushrooms will emerge from the seams between the log sections. Keep the totems in shade, and water during dry weather. Oyster mushrooms can fruit up to three times in a growing season, but lions mane typically only fruits once a year, in the fall.
Growing in beds
Wine cap and almond agaricus are grown in beds but require different substrates. Wine cap mushrooms need hardwood woodchips or straw. Freshness of the woodchips is not as important as when growing on logs or totems. Woodchips that are 6 months old are perfectly fine for growing wine caps. Wine caps can be inoculated anytime during the growing season and can take 2 to 6 months to start fruiting. To inoculate, layer spawn and woodchips like a lasagna. Over time, the woodchips will break down and more will need to be added, especially before winter.
Almond agaricus, a cousin of the white button mushroom and portabella, is grown in compost. Inoculate compost beds any time after the last frost until June. To inoculate, break off egg sized pieces of spawn and bury them at different depths on 6 to 8 inch centers in a grid pattern. Mulch the bed with straw, shredded paper or cardboard to hold in moisture. Mushrooms will start to appear in about 3 weeks and will flush about every 2 to 3 weeks. Typically, the biggest problem is keeping the compost moist enough. It should have enough moisture so that when you pick up a handful and squeeze it, a couple of drops of water come out.
Growing mushrooms is a unique and rewarding way to produce fresh food right in your backyard. With a bit of care, your logs, totems, or beds can produce for several seasons. To learn more or get additional support, contact North Carolina Cooperative Extension- Richmond County Center at 910-997-8255.