In many senses, growing mushrooms outdoors is ideal because the forest (or any shady environment with good humidity and air flow) creates the ideal conditions for fruiting without the need for any climate control on the part of the farmer. Indeed, the forest is where the mushrooms we grow come from, so why not simply grow them there? For centuries, mushroom cultivators have been growing mushrooms on logs in the woods. Ken Mudge professor emeritus at Cornell University researched several species of forest-grown mushrooms for almost 15 years. He explored lion’s mane on totems, oyster on logs, wine cap stropharia on woodchips, and other minor species. In the end, he, along with most outdoor growers, focused on log-grown shiitake mushrooms, as they proved to have the most economic viability.

The main limit with these methods is that out of the species listed above, only the log-grown shiitake can be grown consistently enough to yield mushrooms on a weekly basis, a necessary part of the supply chain for a farm business. This is due to the unique property that shiitake logs can be soaked or “forced” to fruit by immersing the logs in water for 12-24 hours, which stimulates them to fruit. This method can be utilized to produce mushrooms quite reliably from around the first week in June through the middle to late part of October, at least in the climate of Central New York state. If you are further north, you can expect a shorter season, and further south, a longer one. The other species, while successful, fruit on their own time, and so are not good choices if the goal is to produce consistent yields for markets. What many commercial growers are now finding out is that supplemented sawdust blocks fruit amazingly well, on a reliable schedule during those similar months outdoors. As more businesses offer “ready-to-fruit” blocks for sale this option is becoming more feasible and economical for interested growers. In China, a large majority of commercial production is oriented around this system. Large scale industrial farms produce ready-to-fruit blocks and sell them to small scale farms. The farms are in ideal environments for production and, using minimal infrastructure, seasonally fruit the mushrooms. The mushrooms are primarily dried and then shipped to cities for sale. If this method is translated to the U.S., one key consideration is that the American consumer highly values fresh produce, so small-scale farms should be located close to the consumer.

As compared to indoor systems, the required infrastructure and start-up capital for outdoor mushrooms are low. Over their life cycle outdoor systems use considerably less energy as compared to indoor systems (other than in spawn production and inoculation). Outdoor systems can also support sound forest management practices, since we can directly link the materials (logs, stumps, woodchips, sawdust, etc.) to sustainable practices. However, outdoor mushroom production has its limits. For many growers, the market demands that more species than just shiitake be grown. In addition, those in urban and peri-urban areas may find it difficult to access logs or a shady woodlot. And the realities of a dynamic (and rapidly changing) climate mean that production cycles outdoors are unpredictable than indoors.