Is it Time to Fruit Your Mushroom Logs?
by Jim Gouin
Here in Olympia, Washington we've already had some well-deserved warm and sunny days which tend to lure us outdoors after a long wet Pacific Northwest winter. Upon strolling through the forest recently I noticed some young Oyster mushrooms emerging from a fallen alder, triggering a thought—perhaps it's time to soak my mushroom logs! Depending on where you're located in the world, you might be in a similar situation.
Depending on your bioregion, late spring through fall tends to be the best time of the year for fruiting mushroom logs outdoors. Of course you will also need to be within the recommended temperature range of the mushroom species you're trying to fruit. One of the most common questions our customer service representatives hear at this time of the year is, “I purchased some plug spawn last year, plugged my logs according to the instructions and haven't seen any mushrooms yet.” As mushroom cultivators, it's important to observe how mushrooms grow in the wild and attempt to simulate that process as best as possible at home.
Because most mushrooms are approximately 85% water, the substrate material supporting the fungal colony needs to have sufficient moisture in order to produce mushrooms. Basically, by soaking the logs in fresh water for 24 hours you're attempting to simulate a heavy rainfall which tends to trigger mushroom production. Once you've provided the proper moisture and temperature you're on the way to producing mushrooms.
If you don't have mushroom logs yet, now is also a great time to start some. In many areas of North America late winter is the best time to cut your logs because the moisture and sugars within the tree are at their highest. Spring through early summer is usually the best time to inoculate those logs because the average daily temperatures (50–75 °F) are usually more favorable for fungal mycelium growth. This allows the mycelium to aggressively colonize the wood before the native competitors try to take hold. Since it takes approximately 9–12 months for the fungus to sufficiently colonize the logs, you'll be attempting to fruit logs which were inoculated in previous years. It's always a good idea to try and add logs to your rotation every year because the average production life of a deciduous hardwood log is 3–5 years, depending on the tree species. This ensures you'll always have viable colonized logs in the rotation.
After the 24 hour soaking process we find it best to keep the logs in a somewhat shaded location to prevent dehydration. It's advisable to mist or water the logs 1–2 times daily until you start to see mushroom primordia (baby mushrooms) emerge from the logs. This will usually take 7–10 days depending on the temperature and humidity. Shiitake (shown here) prefers a temperature range of 50–70 °F with humidity around 85%.
As the Shiitake mushroom matures it will increase in size and eventually the veil on the underside breaks, exposing the gills. The best time to harvest mushrooms is when the edge of the mushroom cap is still “in-rolled” and not fluted upward. Harvesting mushrooms when they are younger provides longer shelf life and reduces spore production. Mushrooms grown outdoors, especially Shiitake, tend to be more desirable because they grow more slowly, are darker in color, and have thicker flesh. My family has learned to appreciate and enjoy the outdoor grown mushrooms over the indoor produced varieties for these reasons.
Once your logs have been harvested, it's best to lay them back in the incubation piles so they can store up more nutrients for future crops. Depending on your environment you might be able to fruit the logs 2–4 times a year, however it is recommended to let the logs rest about 1 month after a harvest.
Now that we've walked you through the process, go out and check your logs. You might be pleasantly surprised to see some mushrooms already forming. If not, go ahead and give your logs a well-deserved soak. Hopefully you'll have some delicious natural log-grown mushrooms in the near future.
For more information on log and stump cultivation of mushrooms, visit the Plug Spawn section of our site.
Jim Gouin has worked in many capacities at Fungi Perfecti over the last 15 years including laboratory and growroom technician, customer service representative and field mycologist. When Jim is not helping customers or teaching seminars on mushroom cultivation you can usually bet he's either gardening at home, riding his bike or on a fantastic fungal foray.