Growing Mushrooms in the Garden

by Barbara J. Euser

On a recent Saturday, I spent the afternoon at the Presidio Community Garden learning how to grow edible mushrooms. This is different than seeking and trying to identify various species of wild mushrooms that grow in my garden. Whereas wild mushrooms are fascinating to pick and match with photos and descriptions – in order to determine whether they are edible, “pukey poisonous” or downright deadly – growing mushrooms is as intentional as planting a rose.

Ken Litchfield of the Mycological Society of San Francisco (MSSF) gave us a thorough grounding in mushroom cultivation. He explained that the mushrooms we eat are the fruit of the mushroom “plant.” Mushrooms, species of fungus, used to be classified taxonomically as plants, but fungi are now a separate kingdom. The fungus “plant” itself is the whitish web of mycelium that threads its way through a substrate such as decomposing leaves, wood chips, sawdust, hay, or compost. Since the fungus is underground, we don’t see it. When conditions are right, the mycelium produces its “fruit” – that is, the mushroom that contains the spores from which new mycelium could grow. We can harvest mushrooms from our gardens just as we harvest tomatoes or beans.

Mushroom mycelium can be purchased from sources such as Fungi Perfecti of Washington, www.fungii.com; Far West Fungi of San Francisco at 650-871-0786; or Mushroom Adventures at 415-586-4082, www.mushroomadventures.com. Mushrooms can also be grown from cuttings.

Just as one prepares soil for garden plants, the gardener must prepare the substrate for mushrooms. At the Presidio Community Garden, Litchfield had us spread finely ground, wet wood chips about nine inches deep in a shady bed. Fresh hardwood chips are best. They may be obtained from a tree cutting company. Eucalyptus and softwood evergreens, such as pine, spruce, fir and cedar, contain chemicals that only certain mushrooms can tolerate. Hay, leaves, humus or compost may also be used as substrate. Check to see what type of substrate the mushroom you are planting prefers. Litchfield then gave us chunks of mycelium that we buried in the wood chips and watered thoroughly. The mycelium will grow through the wood chips, extracting the nutrients it requires as it decays the wood.

Mushrooms can be grown in wood chips or other substrate in planter boxes or containers. It is critical to keep the containers shaded and damp, as they will dry out faster than substrate on the ground.

Mushrooms can be grown inside. At the annual MSSF Fungus Fair in December, I purchased a tree-oyster mini-farm from Far West Fungi: a block of substrate grown through with mycelium. I put it in my utility room, slit its plastic bag as directed and misted it with water a couple of times each day. The first flush of mushrooms has already delicately flavored scrambled eggs, risotto and other dishes. After I have harvested the second or third flush, I will break up the block of substrate and plant it in my garden.

Mushrooms may also be planted in freshly cut logs. This method uses inch-long, ¼ inch diameter wooden dowels that have been coated with mycelium of a wood-eating species. To plant, drill holes several inches deep in the log, squirt in some water, and push three or four dowels into the holes. To keep the moisture in, plug the end of the hole with wax. This is a project for a patient gardener. It takes a year or two for the log to become fully infiltrated by mycelium. Only then will the mycelium begin to fruit. The log should continue to bear mushrooms for two to four more years. One hundred mushroom-coated dowels cost about $12. During our Saturday afternoon seminar, we took turns drilling holes and plugging them with dowels. I liked the idea, but I need more immediate results.

According to Litchfield, one can grow mushrooms from cuttings from either grocery store or wild mushrooms. Layer mushroom bases, with or without attached mycelium, between pieces of damp, unwaxed cardboard. Place the layers in a closed plastic bag to keep them damp until the mycelium has grown throughout the substrate. Then the layers can be planted in additional substrate in the garden. If the cuttings were taken from wild mushrooms, try to duplicate the conditions where they were picked.

In addition to oyster mushrooms, garden giant, coral mushrooms, blewits, shaggy manes and giant morels are popular species for cultivation.

Litchfield’s excellent seminar and the pleasure I have derived from my mushroom mini-farm have convinced me of the value of cultivating mushrooms in my garden. I know a shady spot that will be greatly improved by a deep cover of wood chips.