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How to Grow Mushrooms on Logs, Pillars, and Stumps

How to Grow Mushrooms on Logs, Pillars, and Stumps

Growing mushrooms on logs is an easy way to ensure you'll be harvesting mushrooms for years to come! After inoculation, logs are relatively low maintenance and you can grow several types of mushrooms in the same space.

Here's what you need to know to get started:

Video Guide

In this video, North Spore's head mycologist Jon walks you through the steps of choosing and inoculating a mushroom log. He covers how to choose the right tree to fell, what tools to use, how to inoculate with sawdust spawn, and proper storage of logs.

Selecting your spawn

There are two styles of spawn we commonly use for growing mushrooms on logs: plug spawn and sawdust spawn. For smaller projects, or if you're not ready to invest in equipment, plug spawn is ideal. To make it convenient and save you a little money, we've put together our outdoor mushroom log kits. Inside is everything you need to inoculate 1-4 logs, including spawn plugs, wax, a drill bit, and wax applicator.

In this video, Jon unboxes a shiitake kit and inoculates an oak log.

There are two styles of spawn we commonly use for growing mushrooms on logs: plug spawn and sawdust spawn. For smaller projects, home-scale grows, or if you're not ready to invest in equipment plug spawn is ideal. To make it convenient and save you a little money, we've put together our Mushroom Log Grow Kits. Inside is everything you need to inoculate 1-4 logs, including spawn plugs, wax, a drill bit, and wax applicator.

If you're inoculating more than 8 logs or are looking to maximize efficiency, choose sawdust spawn. This type of spawn colonizes about 30% faster than plugs but requires some extra tools. One 5lb. bag will inoculate anywhere between 10-40 logs.

To get a more accurate idea of how much spawn you'll need use this handy log inoculation calculator.

If you're inoculating more than eight logs or are looking to maximize efficiency, choose sawdust spawn. This type of spawn colonizes about 30% faster than plugs but requires some extra tools. One 5lb. bag will inoculate anywhere between 10-40 logs. (To get a more accurate idea of how much spawn use this log inoculation calculator.)

When choosing which mushroom to grow, it's also important to know what tree species are in your area and what type of wood may be available to you. Most mushrooms grow well on a wide range of hardwoods, but a few are particular in their preferences. Finding the ideal tree species for your project will increase your chances of success and likely reward you with handfuls of mushrooms. Match your mushroom to trees in our chart below or follow this link.

Mushroom & tree species compatibility

Log size:

We recommend sourcing logs from a sustainable forester or using sustainable practices in culling trees for mushroom production. For more information on selecting tree species for mushroom growing,
follow this link.

Log inoculation

Healthy, living trees can be felled for mushroom logs nearly any time of year. Generally, fall is an ideal time. It is not recommended to harvest logs during the spring between bud swell and full leaf out. During this time, most of the nutrients and energy of the tree are expended in a push to develop flowers and foliage, leaving little for fungal growth. Also, bark is loose, increasing the risk of damage during cutting. Intact bark is very important for the spawn run. Never cut dead, dying, or diseased trees for mushroom growing.

Log size

Any size logs will work. You can use branches or saplings, if that is what you have available. Small-diameter wood will colonize faster, but will not produce for as many seasons as a larger log. You don’t want the logs to be so large or heavy that they are difficult to use. For drilling methods, a 4-6’’ diameter with a 3-4’ length is ideal. For the pillar (aka totem) method, they can be up to a foot (or more!) in diameter, and 6-18’’ high.

We recommend sourcing logs from a sustainable forester or using sustainable practices in culling trees for mushroom production. For more information on selecting tree species for mushroom growing,
follow this link.

Methods of inoculation

There are two main methods of inoculating, the traditional log method and the pillar (aka totem) method. The traditional method works well for most mushrooms that grow on logs and can be adapted to use on stumps, too. We can trace its use back thousands of years to modern day Japan! The wonderful thing about mushroom logs is that you will get multiple years worth of gourmet mushrooms without having to re-inoculate your logs. On average, a mushroom log will produce for 1 year per inch of diameter of the log. So, if you inoculated a 5-inch diameter oak log with shiitake spawn, it will most likely produce for 5 years!

Timing your inoculation

Logs should be inoculated within a week or two of cutting. This allows the cells in the tree to die but is not long enough for the log to dry out or for other competitor fungi to become established. One month would be about the longest reasonable stretch of time between cutting and inoculating your logs. When temperatures are consistently below freezing, the window for inoculation can be extended for several months. Freshly cut wood can be covered with snow to maintain moisture until you are ready to inoculate in early spring.

Traditional log method

For drilling methods, a 4-6’’ diameter with a 3-4’ length is ideal.

Larger logs can be used but you don’t want the logs to be so heavy that they are difficult to move.

1. 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.

2. 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.

3. 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 away the wax so allocating a thrift store crockpot or bowl to the job is a good idea.

Stump method

Stumps take longer than logs to colonize but can produce for up to a decade.

Any size stumps can be inoculated, but they should be from freshly cut trees. All inoculated stumps should be located in a shady environment. Make sure you can identify the stump and you know what species of tree it is!

1. Girdle your stump by removing a two inch wide band of bark, make sure to remove both the outer and inner layers of the bark. This helps to prevent suckers from growing.

2. 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’’ all over the top, sides, and exposed roots of the stump.

3. 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 sawdust spawn into the holes.

4. 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 away the wax so allocating a thrift store crockpot or bowl to the job is a good idea.

Pillar (aka totem) method

In the pillar method, smaller sections of logs are stacked upright with sawdust spawn sandwiched between. No special tools are needed for this no-fuss technique and large-diameter wood becomes easy to use and attractive to display. This is the preferred method for oyster mushrooms, lion's mane, and reishi which naturally fruit when temperatures shift in the spring and fall. One 5lb bag of sawdust spawn should be enough to inoculate three or four 10-12" diameter stacks.

1. Cut three sections of log for each pillar: one piece only 2’’ long, and two sections 6’’ to 18’’ long.

2. Bring your supplies to your shady incubation place and create the pillars on site.

3. Lay a piece of brown cardboard or a kraft paper bag on the ground, sprinkle on a layer of sawdust spawn about 1’’ deep, and stand one of the 6’’-18’’ pieces upright on top of the spawn. Add another layer of sawdust spawn on top of this section and stand the next 6’’-18’’ section on top. Add one last layer of sawdust spawn on this section and then cap the pillar with the remaining 2’’ piece. Place an overturned paper lawn and leaf bag over your pillar. Tuck it under at the bottom or add weight to keep in place. The bag will help keep in moisture and keep out contaminants and pests.

4. Incubate the covered pillars for 4-12 months. When the logs are covered with a visible layer of mushroom mycelium (white mold-like substance) the paper bag can be removed. The pillar can be left intact or broken up into individual sections for fruiting.

Trenching or burying your logs

Burying or partially burying logs has been found to be critical to the successful fruiting of a few specific species. The advantages of burying or trenching these logs include additional moisture around the logs, beneficial microbes in the soil and triggers for fruit body development including light and oxygen limited to a smaller surface area.

We recommend burying or trenching hen of the woods, chicken of the woods, chestnut, nameko and reishi logs after full colonization. One way to check if your log is colonized is by looking for mycelium on the ends of your logs. Mycelium does not always cover the entire end but should be visible on most of the end, either on the surface or under the wax. If no mycelium is visible you can use the average colonization time of the species you selected. If in doubt we recommend waiting approximately one year in areas with snowy winters while those in areas with mild winters could trench their logs after three seasons have passed. Keep in mind larger diameter logs will take longer to colonize.

In order to trench your logs, dig out an area half as deep as the diameter of your logs in a shaded location. Reserve the soil you remove from this area. Place your logs in your dug trench in a raft formation. Then take your reserved soil and pack it around and between the logs so only the top surface area of the logs are exposed. For chestnut and nameko, wood chips or sawdust can be used in addition to or in place of soil. Water the area so the material around your logs compacts and add more if necessary!

Post inoculation

The time between inoculation and first harvest will depend on what species you’re growing, the size of your logs, and environmental conditions. Most mushrooms on standard size logs in temperate climates will take about a year to fully colonize before they fruit. This can vary between 6 months to two years. Smaller diameter logs and soft hardwoods will typically fruit sooner, though they’ll have less longevity.

Often, mushrooms need cool weather and moisture to fruit. Growth slows in the heat of the summer. If you inoculate in the spring, you might get your first flush of mushrooms in the fall but most likely it will take a full year until you see your first fruiting. If you inoculate in the fall and are able to keep the mycelium from going dormant, you may get mushrooms as soon as the next spring, though more likely the following fall.

Mushroom log yields depend on the type of wood chosen, the species you are inoculating, and environmental conditions. Generally speaking, dense hardwoods take longer to fully colonize but will continue to fruit for more years, while soft hardwoods (like poplar) will fruit sooner for fewer years. And wood with more sapwood than heartwood may yield more mushrooms.

Speed up your mushroom log inoculations with the Trio of Tools. An angle grinder adapter and 12mm drill bit to drill holes quickly, and an inoculation tool to fill them with sawdust spawn.

Maintenance and fruiting

Incubate logs in a shady place, close to the forest floor but not in contact with soil or leaf litter. Lay down tracks of scrap wood that elevate the logs 1-2'' above the forest floor. Stack the logs in a layer with a little space for airflow between each log. If you have more logs, you can make multiple layers by off-setting each layer by 90°. Keep the stack lower than the average snow line, as the snow cover protects the logs from dry winter winds.

Generally, no special care is needed while the mycelium grows throughout the log, but watering may be needed if excessively dry weather occurs. Logs shouldn’t stay wet on the outside for long periods of time. Frequent light watering can even damage logs and cause contaminant growth. Long periodic soaking of no more than 24 hours is the preferred method of renewing water content should your logs appear dry or lose vitality.

Restack the logs into a log cabin fashion for increased airflow and ease of mushroom picking, about a year after inoculation. Log cabin stacks can be as high as 5' in wetter climates but in dry climates shorter stacks, closer to the ground, help keep logs moist.

Fruiting naturally occurs after rains and occurs in cycles. After the log has fruited once on its own, it can be stimulated to fruit by watering or soaking it in cold water for no more than 24 hours. Force fruiting works best with shiitake mushrooms. Allow at least one month of rest before attempting to force fruit again. If it has recently fruited, forcing will probably not work.

First year incubation and winter stacking pattern

This method keeps logs low to the ground to prevent moisture loss, especially in winter months.

Second year log cabin style stacking pattern

This method is ideal for increased airflow and ease of harvesting, once logs have properly incubated.

Image courtesy of @yalelandscapelab on Instagram

If you have more questions, head over to our Spawn FAQ for some troubleshooting tips.

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How to Grow Mushrooms on Logs, Pillars, and Stumps

Video Guide

Selecting your spawn

Mushroom & tree species compatibility