Fall is a great time to start inoculating oak logs for outdoor mushroom growing. By getting a head start in autumn, you give the mycelium plenty of time to settle in and grow before spring arrives. Oak logs are strong and packed with nutrients, making them perfect for growing mushrooms like shiitake, reishi, lion’s mane, and more. Plus, they can keep producing mushrooms for years, so you'll be able to enjoy fresh harvests for a long time. If you’re thinking about starting a mushroom-growing project, fall is the perfect time to dive in!
Why is oak ideal for growing mushrooms?
Oak is one of the best hardwoods for growing mushrooms. Its dense, tannin-rich wood is slow-decaying, and provides a long-term source of nutrients for various mushroom species.
Oak logs can support mushroom growth for years, making them a great investment for long-term cultivation. Oaks come in many varieties and occur in most areas of the United States, making it an abundant resource as well. In fact, many hardwood-based substrates used in mushroom cultivation are made of oak for these reasons.
Which mushrooms grow on oak logs?
• Shiitake (Lentinula edodes): One of the oldest cultivated mushrooms, shiitake have a meaty texture and a rich umami flavor, making them a favorite for cooking. They grow best on oak logs and can keep producing mushrooms for over a decade, yielding multiple pounds per season.
• Blue Oyster (Pleurotus ostreatus): Blue oyster mushrooms are fast-growing and easy for beginners to cultivate. They adapt to a variety of conditions and thrive on softer hardwoods like Aspen and Willow, but are suitably grown on oak as well. They are reliable and popular for home mushroom farming.
• Reishi (Ganoderma lucidum): Famous for their medicinal properties, particularly their immune-boosting benefits, reishi are often used in teas and tinctures. They grow best in warm, humid conditions, and logs should be placed on the ground or partially buried to help with fruiting.
• Lion's Mane (Hericium erinaceus): Lion's Mane mushrooms have a unique appearance, resembling a white pom-pom or a cluster of icicles. They are prized for their delicate flavor, similar to seafood, and their potential cognitive health benefits. They prefer cooler temperatures and moist conditions to thrive.
• Chestnut (Pholiota adiposa): Chestnut mushrooms have a nutty flavor and crunchy texture, growing in clusters during late summer and fall when temperatures cool to 50-70°F. While they prefer beech trees, they have been found on oak and poplar as well. They require careful moisture control during the incubation phase to ensure healthy growth.
• Nameko (Pholiota nameko): Known for their golden-orange color and slimy cap, nameko mushrooms are commonly used in Japanese cuisine, adding a slightly fruity flavor to soups and stews. They prefer cool temperatures and a damp environment for growth.
• Turkey Tail (Trametes versicolor): Turkey tail mushrooms are vibrant and fan-shaped, with multiple colors resembling a turkey's tail. They are famous for their medicinal uses, especially for supporting the immune system. They grow on decaying wood and can be found in many different kinds of forests.
• Chicken of the Woods (Laetiporus sulphureus): Bright yellow-orange in color and known for their chicken-like taste when cooked, this mushroom grows in large, shelf-like clusters on trees and are easy to spot. Often used as a meat substitute in vegetarian dishes, they are more challenging to cultivate than other species and therefore require extra care and attention during the incubation process.
• Hen of the Woods / Maitake (Grifola frondosa): Widely appreciated for their culinary properties, this gray-brown polypore is rich and flavorful, making it a perfect addition to your favorite mushroom dishes. Hen of the woods mushrooms have a rich, earthy flavor and a firm texture, making them popular in culinary dishes. Typically found at the base of oak trees, this species can be difficult to grow due to competition from other microbes but logs can be steam sterilized for increased success.
Which type of mushroom spawn is best for oak logs?
When starting any mushroom growing project, you’ll want to select the right spawn. Spawn contains mushroom mycelium grown on substrate, and there are different types of spawn you can choose from, depending on the project. In mushroom cultivation, you’ll likely run into three main types: sawdust spawn, plug spawn, and grain spawn. Plug spawn is used in outdoor log kits and is made of wooden dowels with mushroom mycelium grown on them. It’s perfect for beginners; all you need is a drill, hammer, and wax. Sawdust spawn is used similarly to plug spawn, but it requires an inoculation tool to insert the sawdust into drilled holes. It's faster and more efficient than using plug spawn, especially when inoculating for larger or commercial mushroom growing projects. Grain spawn is often used in garden beds and more commonly used in indoor or controlled environments. Grain spawn is not recommended for log projects because it's more likely to be eaten by critters and isn't as easy to secure in the log compared to sawdust or plug spawn.
Can I inoculate mushroom logs in the fall?
Fall is the perfect time to inoculate oak logs with mushroom spawn due to the following factors:
1. Prime Conditions for Mycelial Growth: The cool, wet conditions of fall are ideal for mycelium to establish itself in the wood. Mycelium needs time to grow and colonize the log before fruiting, and fall provides the extended incubation period necessary for faster mushroom production in the spring.
2. Increased Log Nutrient Content: In the fall, trees begin to store nutrients in their trunks as they enter dormancy. When about a third of the tree’s leaves have changed color, it's a sign that the tree has shifted to dormancy, concentrating moisture and sugars in the wood. This nutrient-rich environment is perfect for mushrooms to thrive.
3. Better Log Receptivity: During dormancy, the cells in the wood become more pliable, allowing for improved and faster fungal establishment. This pliability helps the mycelium colonize the log more effectively.
How to inoculate mushroom logs
1. Harvest the Log
• Cut oak logs in the fall, after at least 30% of the leaves have changed color and fallen.
• Logs should be 3-4 feet long and about 4-6 inches in diameter. Larger logs can be used but you don’t want the logs to be so heavy that they are difficult to move.
2. Traditional Log Cultivation Method
• Use a 8.5mm or 5/16’’ bit for plug spawn or a 12mm or 7/16’’ bit for sawdust spawn and drill to a depth of 1’’ in a diamond pattern all over the perimeter of the log, omitting the cut ends. We recommend spacing holes four inches apart in rows that are staggered two inches apart.
• Place plugs into your holes and use a hammer or mallet if the fit is snug. If using sawdust spawn, use an inoculation tool to push the sawdust spawn into the holes.
• Brush melted wax over each plugged hole. We use a crockpot to melt the wax and a wool dauber or paint brush to apply it. The double boiler method can also be used. Sealing the holes is critical to success because it protects the spawn from drying out and from contamination. Keep in mind that it can be difficult to clean out the wax so allocating a thrift store crockpot or bowl to the job is a good idea.
3. Post-Inoculation Care
• Place the inoculated logs in a shady, moist area. Cover the logs with leaves or a tarp to retain moisture and protect them from drying out.
• In areas with harsh winters, consider storing the logs near a heated structure or in a greenhouse for insulation.
• Additional steps can be taken to prepare logs for fruiting including stacking, making pillars, force fruiting, and trenching, depending on the mushroom in question.
Final thoughts on mushrooms for oak logs
Fall and spring are ideal times for mushroom cultivation, and oak logs provide a nutritious substrate for many fungi. The cool and moist conditions of autumn create a perfect environment for mycelial growth, and by starting the process in the fall, growers can extend the incubation period, leading to earlier fruiting the following year. Many of our favorite culinary mushrooms, including shiitake, reishi and lion’s mane grow well on oak logs, making this relatively easy-to-find tree species an ideal substrate for growing nutritious, protein-rich food close to home!