New WSU Extension program growing network of Northwest shiitake producers

A new Washington State University Extension program is teaching aspiring shiitake mushroom farmers how to cultivate the umami delicacy on forest logs.

Profile picture of Justin O'Dea smiling toward the camera. Shiitake growing on logs can also be seen in the photo.
Justin O’Dea, a WSU Extension faculty member and regional agriculture specialist in Vancouver, Wash.

Funded by a USDA Western Sustainable Agriculture Research and Education grant, the program is the first of its kind in the western U.S. and a boon for forest farmers looking to diversify their market offerings.

“We started testing outdoor shiitake cultivation using logs in the Northwest in 2019 and have made promising headway, but there’s still so much to refine about growing shiitake on logs here,” said program leader Justin O’Dea, a WSU Extension faculty member and regional agriculture specialist in Vancouver, Wash.

O’Dea is partnering with Oregon State University Researcher Eric Jones and WSU Extension Forester Patrick Shults to mentor 12 new forest shiitake growers using research-backed cultivation methods. This initial group of Northwest growers will then assist and mentor others interested in producing log-grown shiitake.

Globally, Japan produces the lion’s share of log-grown shiitake, which are used widely in Japanese cuisine. To learn best practices, the research team traveled to the country to glean insights from Japanese growers, industry professionals, and researchers.

“Japan started large-scale production of log-grown shiitake in the 1940s,” O’Dea said. “We were able to capitalize on new understandings that have developed since.”

OSU researcher Shinji Kawai planned the trip’s rigorous travel schedule, which took the team from the south island of Kyushu to Hokkaido, the northernmost prefecture.

Kawai said that the process of planning the trip was a mix of hard work and serendipity.

“Without Justin’s relentless pursuit of best shiitake production practices, I wouldn’t have had the chance encounters with Japanese shiitake industry professionals and interdisciplinary researchers that made this trip successful,” said Kawai.

A flush of hundreds of shiitake mushrooms from dozens of inoculated logs.
A flush of shiitake mushrooms growing from bolts.
Close-up of shiitake growing on logs.
Shiitake mushrooms fruit on this “bolt,” a log that has been inoculated with a strain of shiitake.

He added that the Pacific Northwest’s climate, with its spells of low summertime humidity, presents a hurdle to achieving consistent yields of shiitake.

The U.S. researchers repeatedly heard from Japanese shiitake growers that finding the right strain is key. During their trip, the cohort established ties with a Japanese supplier of shiitake strains that could show promise in the Pacific Northwest’s climate.

“Selecting strains that do well in our climate would create a major change in how we approach production,” said Kawai.

Japanese shiitake growers also advised that Northwest U.S. producers should learn from others in the region who have been successful.

“That was affirming to the mentoring approach we are taking with our new growers,” said O’Dea. “These new Northwest shiitake farmers will eventually be able to provide that mentorship to future growers.”

1982 was the last time a researcher from a U.S. public institution visited Japan to learn about log-based shiitake production. That USDA researcher, Gary Leatham, published an article detailing what he learned from his travels, sparking a new generation of shiitake producers, largely across the eastern U.S.

Participants hope the new WSU Extension program will foster a new generation of shiitake growers on the opposite side of the country.

“We are attempting to develop a foolproof, forest-grown shiitake cultivation methodology for the Pacific Northwest,” said Eric Jones, part of OSU’s College of Forestry. Jones joined the trip to Japan and is excited to collaborate with the WSU researchers on this project.

“From our travels, we know that we’re headed in the right direction” Shults said. “We’re excited to put what we learned into practice to support growers in developing their own log-grown shiitake operation.”

Learning more and getting started

Those interested in learning how to grow shiitake on logs for market can contact Justin O’Dea or Patrick Shults with WSU Extension, or Eric Jones at OSU.

Media contact

Justin O’Dea, Regional Agriculture Specialist, WSU Extension,, 360-524-2383