How to Grow Mushrooms on Logs

Growing mushrooms on logs is the perfect technique for anyone interested in outdoor cultivation. It’s passive, low-tech, and in some ways, more congruent with natural processes than indoor cultivation methods. You don’t need to pasteurize substrates, manipulate growing conditions, or utilize specialized equipment.

While it’s true that mushroom logs may take 8-12 months before producing their first flush (compared to 3-4 weeks with bag-cultivation methods), the good news is that they can produce for multiple years. It’s not uncommon for a well cared for mushroom log to last over 5 or 6 years, sometimes giving multiple flushes per-year.

Another great thing about log cultivation is that it’s easy. There’s a lot less room for error compared to other conventional methods which may be prone to contamination. Practically anyone can do it, and if you take good care of your log and don’t use it as firewood (trust me, this happens), you’re bound to get a harvest. This said, there’s a lot of details and tips which can highly improve your long-term results.

Who Is Log Cultivation For?

• Those interested in low-tech sustainable cultivation methods
• Individuals with access to hardwood trees
• Folks with outdoor space they’d like to utilize
• Gardeners looking to incorporate fungi into their system
• Anyone looking for a passive harvests that require minimal work after inoculation!

What Mushrooms Can Grow On Logs? 

Many desirable gourmet and medicinal mushrooms can be cultivated on logs - while the list of species is constantly changing as cultivators develop new techniques, here is a (not so) short list: 

• Oyster Mushroom (Pluerotus spp.)
• Lion's Mane (Hericium spp.)
• Shiitake (Lentinula edodes)
• Chestnut (Pholiota adiposa)
• Nameko (Pholiota nameko)
• Turkey Tail (Trametes versicolor)
• Reishi (Ganoderma spp.)
• Chicken of the Woods (Laetiporus sulphureus)
• Maitake (Grifola frondosa)

Basics Of Log Cultivation for Mushrooms

The log cultivation of mushrooms can be traced back to at least 800 years to the Song Dynasty in China. These preliminary techniques did not rely on laboratory cultivated spawn but instead natural sources of inoculum present in the environment. The modern method of log cultivation was developed around the early 20th century and has practically remained the same since.

The basic process is as follows;

1. Logs are drilled with numerous evenly spaced holes.
2. Holes are filled with mushroom spawn (check out our guide about spawn if you're interested)
3. The holes are covered with a protective wax.
4. Logs are left to sit in a shady spot while the mycelium (mushroom “roots”) expands from the spawn into the log.
5. After 8-12 months, or when the rainy season occurs, you will monitor your logs for your harvest! In some cases they can be triggered to fruit on demand. (more on that later)

Materials Needed for Mushroom Logs

• Mushroom Spawn: Spawn is the mycelium of the mushroom cultivated on a sterile substrate. For logs the best type of spawn is either plug-spawn or sawdust spawn.
• Plug spawn are small wooden dowels that are colonized with the mushroom mycelium. These can be placed into the drilled holes and jammed inside with a hammer. You will need about 30-50 plugs per log.
• Sawdust spawn can also be used, and in many cases it can colonize faster and more aggressively. It’s recommended to utilize an inoculation-tool to make it easier.
• Grain spawn can be used but isn’t generally recommended since it is more likely to get contaminated or eaten by an animal. A 1lbs (0.5 kg) bag of spawn is typically more than enough for 4-6 logs.
• Hardwood Logs: These should be freshly cut and around 4-6 inches in diameter and 3-4 feet long. We’ll discuss this more later.
  
  
• Drill and Drill Bit: If you’re going to be drilling a lot of logs, we recommend you utilize a plugin drill instead of a cordless one
• For plug spawn you usually want an 8.5 mm drill bit, but this could vary slightly depending on your spawn producer. It’s worth asking.
• If you’re going to inoculate with sawdust spawn you can use a 12mm drill bit.
  
  
• Wax and Dauber or Brush: After filling your logs with spawn, the openings are covered with wax to protect it from the environment. While it may be attractive to utilize bees wax, it’s preferable to utilize soy, cheese wax, or even paraffin wax, as they are more resistant to environmental changes and pests.
  
  
• 70% Alcohol: While not strictly necessary, it doesn’t hurt to disinfect your hands and tools before starting.
  
  
• Work Table or Sawhorses: Also not necessary, but it can save your back, especially if you are making many logs.
• Our Mushroom Log Starter Kits contain mushroom spawn, wax, dauber, and drill bit to help you get started! 

Recommended Species For Log Cultivation

Almost all gourmet and medicinal mushroom species work well for log cultivation. This includes Oysters, Reishi, Pholiota, Turkey Tail, and Shiitake. Lion's Mane can also be cultivated on logs, although it tends to be much slower.

Selecting and Harvesting Logs

Depending on where you are located you’ll have different species of trees available for log cultivation. Each tree species has unique characteristics, and many may have preferential qualities for specific species of mushrooms.

• Utilize Hardwood Logs: Hardwoods are broadleaf tree species like Oak, Maple, Alder, Walnut, and all fruit trees. These are preferential for mushroom cultivation, although some hardwoods are better suited than others. Softwoods are coniferous needle-bearing trees like Pine, Spruce, and Fir, and are not recommended.
  
  
• Use “Freshly” Cut Logs: Logs should be used no more than 3-4 months after they’ve been cut. This ensures that no other competing fungi have taken hold on the log. This said, it’s recommended to wait at least 3-4 weeks after cutting as it gives time for some anti-fungal compounds in the wood to break down.
  
  
• Use Healthy Logs: Avoid logs that look unhealthy, having cracking bark, or are already displaying signs of rot. These logs will likely already be colonized by a competing fungi.
  
  
• Use Logs 4-6 Inches in Diameter and 3-4 Feet Long: Larger diameter logs take longer to colonize and can be more cumbersome to handle. About 3-4 feet is an ideal length as they are still easy to move and handle at this size. Realistically, you can use logs of any size but these specifications mentioned will give you the most consistent results.
  
  
• Remove Moss, Lichens and Debris: This can help lower incidence of contamination. You can do this by hand or with a sturdy stiff-bristled brush. Avoid damaging the bark during this process.

Drilling Holes for Mushroom Log Inoculation

Drilling the holes is one of the most labor-intensive parts of the process. It’s recommended that you have a good trusty drill for this process. A plug-in drill is often your best option as they often have more power and avoids the risk of running out of battery mid-process.

Hole Size and Depth for Mushroom Log Inoculation

Hole Spacing

The adequate spacing for holes is about 4-6” (10-16 cm) apart in an alternating diamond pattern. It’s easiest to just go row by row and keep a steady momentum when doing it. The closer the holes are spaced apart the faster the colonization, while widely spaced holes will result in slower colonization.

• Drill a row of holes along the length of the log.
• Rotate the log and drill a second row, offsetting the holes so they fall halfway between the holes in the previous row.
• Continue around the log until you've covered the entire circumference.

Note: Spacing is approximate, and doesn’t have to be perfect.

Inoculating The Log With Mushroom Spawn

The inoculation process is where you introduce your spawn into your log. While the principle is pretty much the same, the process is a bit different depending on the type of spawn you use.

Plug Spawn: Simply place the dowels into the hole and hammer them in until they are flush with the bark! It can save you time to fill half the log with your dowels, hammer them in, and then do the other half.

Sawdust Spawn: To begin, make sure your inoculation tool is clean. If you have alcohol, it’s recommended to disinfect it first. Then simply jam your inoculation tool into your bag of spawn, filling the entirety of the chamber. Once full, fill the holes with spawn.

An inoculation tool is highly recommended for efficiency. If you don't have a specialized inoculation tool, you can create one using a metal tube fitted to the size of your drilled holes. Use a plunger or dowel rod to push the spawn from the top of the tube into the hole.

Log Alternative: Totem Method

While we hope to cover this in an entire article, an alternative method for log cultivation is doing the so-called “Totem-Method”. This involves utilizing wide diameter logs (1-3 ft) that are about 1 ft in height. These can be "sandwiched" with layers of sawdust spawn and incubated with a large plastic bag on top. This method is excellent for large diameter logs and may even be quicker with some species. It is less common, but many people have success with it.

Sealing With Wax

Once your log is inoculated, it is time to seal your inoculated holes with wax. This helps retain moisture, prevent contamination, and generally protects the mycelium from the external environment. This is particularly crucial for the initial phase of colonization.

We recommend you utilize paraffin or cheese wax for this process. Both of these are effective for sealing and withstand diverse environmental conditions. Beeswax can work, but it tends to crack with cold temperatures and become undone with time, leaving your precious mycelium susceptible to hungry mycelium-eating pests.

Melting the wax

First, you'll need to melt your wax before application. We recommend using a pot you don’t really care too much about, just in case it gets damaged during the process. It’s good to utilize a portable heating element like a hot plate or camp stove if you have one, to avoid having to transport the hot wax very far. Make sure to monitor the wax and utilize it once it’s completely liquid. At this point turn the temperature all the way down or remove it from the heating element. If you start seeing smoke, you should quickly remove it from the heat. Alternatively you can use a double-boiler to reduce the risk of burning your wax.

Safety Note: Exercise caution when working with hot wax, as it is flammable. Ensure the melting area is well-ventilated and away from any flammable materials. Never leave melting wax unattended.

Apply the wax

To apply the wax you’ll want to either use a foam paintbrush (recommended), a cotton dauber, or a regular brush. The goal is to cover each hole with a thin-layer of wax to create a thorough seal. If you live in a very biodiverse environment (such as a forest or jungle) you may want to consider doing double-layers to prevent mycelium-loving critters from boring their way through the wax. It’s also recommended to seal the ends of the logs to prevent moisture loss. Remember to work quickly and apply the wax while it's still hot and fluid. This ensures a good seal and prevents the wax from cooling and hardening prematurely, which can cause poor adhesion or chipping off over time.

Incubation

Once sealed with wax, your log is pretty much ready to go, and all you need to do is wait for it to colonize! To ensure the colonization happens without any issues, it is crucial to select a good area for incubation. The incubation process is typically about 6-12 months, but can be as much as 24 months in some cases. Below are some tips to help you with this process.

Keep Logs Off The Ground: Generally speaking, it is recommended to keep your logs off the ground as much as possible. This helps prevent contamination. Stacking them on top of two "sacrifice" logs can work or utilize a pallet. If you decide to lean your logs, it’s okay if one end is touching the ground. This said, fully colonized logs can be partially buried to help with moisture retention.

Keep In Shady Protected Area: Avoid stacking your logs in direct sunlight or in very windy areas. This can cause them to dry out quickly and inhibit the growth of your mycelium. Under some trees is often the best option. Underneath a porch can also be a great place. If you experience really extreme dry temperatures, you may want to place a tarp or shade cloth on top of your logs to help retain moisture.

Below Snow Depth: If you are in an area which receives a lot of snow, it is recommended to keep your stacks low to the ground. This allows them to be protected by a blanket of snow during the winter. If your logs are stacked above your snow depth, they can easily dry out and experience much colder temperatures during the winter.

Stacking Methods: There are many different stacking methods. The “lincoln log” stack is a classic and allows for easy harvesting. If you are tight on space you can also have 3-5 logs per layer in the stack. Some growers like the A-Frame or the Leaning method where one end is on the ground and the other supported on a fence.

Watering: Watering is usually not necessary but can help speed up the colonization process, especially in drier environments where rain doesn’t do this naturally. For this to really work it must be somewhat consistent, about 2-3 times per week is fine.

Monitoring: Regularly inspect the logs for signs of colonization or fruiting. You should see white mycelium growth on the ends of the logs and sometimes around the inoculation points. After 6-8 months you will also want to regularly check for mushrooms which may appear naturally during the rainy season.

Patience: Logs require patience – in exchange for the easy, low-tech approach, you are giving up some of the control to natural processes and seasonal cycles, so embrace and enjoy that. Low-density woods and fast colonizing species like Oysters can be colonized in as little as 6 months. High density woods and slow growing species like Lion's Mane can take up to 24 months.

Fruiting and Harvest

After you’ve waited at least 6-8 months may want to trigger fruiting. You can do this by soaking your logs for 12-24 hours in cold water. Cold temperatures and the rehydration of the log is often enough to stimulate the formation of mushroom fruiting bodies. In Japan, farmers will often smack Shiitake logs with large mallets to stimulate fruiting.

Each mushroom has its own prime-time for harvesting. You can learn more about this in our Introduction to Fruiting article. We recommend you pick the entire mushroom as opposed to cutting them, as leaving stem-butts behind can invite unwanted critters to come feast on your mushrooms!

Conclusion

Growing mushrooms on logs is a great and easy way to cultivate your own mushrooms. It’s a relatively easy process which can really pay off in the long term as long as you have patience!

If you have any more questions we recommend you check out our introductory article series on mushroom cultivation. While these articles are more focused on conventional bag-cultivation techniques, they can still provide a lot of insight into the basics for cultivation and fungal biology.