A-Horizon Ventures Enables Gardeners to Grow Mushrooms at Home

The fungal goodies are good to eat, good for the soil, and good for the environment.


Photo by Susan Kuchinskas

It’s a misty morning in rain-soaked Mosswood Park, and that means it’s a great day for mushrooms. Justin McDavid is about to turn the massive logs from a century-old oak tree into mushroom patches.

The tree succumbed last summer to overwatering and an invasion of California oak moths. Instead of hauling it to the dump, the city cut it up and left the logs for the garden. McDavid laid them around the perimeters of beds in the Mosswood Community Garden, for which he’s the volunteer site coordinator. Today, he’ll make deep cuts into the logs with a chainsaw. Then, he’ll add fungal mycelium, a thready white mass that intertwines with the wood and breaks it down. If all goes well, in a few years, flushes of edible mushrooms will appear.

Good eating is just one part of the mushroom story. These simple plants can have profound effects on the health of your garden’s soil — and benefit the environment.

Decomposer fungi break down dead trees or logs, unlocking their nutrients and making them available to other organisms, including insects and plants. Letting mushrooms decompose wood also puts some of the carbon they contain back into the ground instead of the air.

Mushrooms are a sustainable way to get rid of tree stumps, too. The edible maitake will cause the roots of an oak to rot, while the edible phoenix oyster mushroom will devour a pine stump.

McDavid started A-Horizon Ventures to promote fungi as a tool for regenerating damaged soil and sequestering carbon. He also provides mushroom spawn, that is, mycelium that’s been grown on small pieces of wooden dowel, for home gardeners.

To start your own mushroom patch, all you need are a log, spawn, and a damp, shady place.

If you’ve done some serious pruning or have an entire tree to take down, instead of having it hauled away, ask the tree service to cut it into 4-foot sections. Or keep an eye out for a tree service working in your areas; they’re usually happy to get rid of logs.

Drill a series of holes all around the log, push in pieces of spawn-soaked dowel, and seal the holes with wax. Stack them in a shady part of the garden, and you’ve got a tiny ecosystem that may produce for years, leaving you in the end with a rich patch of soil. Smaller logs may produce mushrooms in a year or two, while thicker logs take longer.

Currently, A-Horizon sells packets of spawn and inoculated logs through urban farm stores BioFuel Oasis and Pollinate. Choose from species including maitake, shiitake, blue oyster, elm oyster, trainwrecker, bear’s head, nameko, turkey tail, and lion’s mane. McDavid will also travel to people’s gardens or land to inoculate fallen trees in situ, and he’ll teach a series of classes throughout the East Bay this spring and summer.

His goal: to spread more fungus among us.

Learn more at A-Horizon.ventures; BioFuel Oasis, 1441 Ashby Ave., Berkeley, 510-665-5509; and Pollinate Farm and Garden, 2727 Fruitvale Ave., Oakland, 510-686-3493.