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Ouotdoor Mushroom Cultivation Directions

stacked logs


What is Plug Spawn?

Plug spawn consists of small pegs of wood that are colonized by mushroom mycelium. It is a convenient way to inoculate a log with a mushroom. The basic idea is to drill holes in a log and put the pegs in the holes. The mycelium then grows out from the pegs and into the log.

Log size

Logs used for cultivation are usually 4 to 6 inches (10 to 15 cm) in diameter, but smaller or larger sizes can be used. Smaller logs tend to have a shorter life span - they begin to produce mushrooms sooner, and become exhausted sooner. Small logs also dry out more quickly, so they require more frequent attention. For reishi and maitake, larger logs tend to produce larger individual fruiting bodies, although for oyster mushrooms this isn't usually the case. Of course, larger logs are more difficult to handle and move, something to consider if you plan to submerge logs to induce fruiting, a common practice in shiitake log cultivation.

Log species

It is critical to use the right tree species for a given mushroom species. The oyster mushroom is a generalist, and will do well on just about any species of hardwood (broadleaf tree). Maitake grows best on oaks stumps and Shiitake grows best on oak logs. Maitake and Shiitake can also grow on other non-aromatic deciduous trees such as maple or beech, but we don't recommend inoculating these species on anything other than oak without ensuring the strain you are using does well on the alternate tree species. American Reishi tends to grow on hemlock. We use Eastern Hemlock, and we expect that our strains would also grow well on Western Hemlock, although we haven't confirmed this yet. While not as common, we have also noticed American Reishi naturally growing on Maple trees in Vermont. The most important rule of any mushroom cultivation project is to start small and gain your own personal experience with the strains of mushrooms you are working with which can thrive on locally abundant (and affordable) substrates.


Ideally, logs should be cut while the tree is dormant - after the leaves fall and before the buds break. This increases the nutrients available for the mushroom, and also helps the bark adhere to the wood. Intact bark is important for preventing contamination and retaining moisture. Many mushroom growers also have success with logs cut during the growing season, this is simply not as optimal as winter-cut logs.

Logs should ideally sit for a week or two between cutting and inoculation. Living wood defends itself against fungi, and this time period allows the tree's "immune system" to break down.

On the other hand, logs shouldn't sit any longer than about 3 months before inoculating, because other fungi will begin to colonize the wood. The exact amount of time before competitors are able to become established depends on a number of factors, including airborne spore load, type of ground and degree of contact with it, log moisture content and tree species.

Other points

Logs intended for mushroom cultivation should be treated gently. If the log is dinged up and the bark is damaged, the wood will be exposed to contaminants - other fungi that will compete with the one you are trying to grow. If the log is dragged through the dirt, contamination risk will also increase. Logs cut in winter and skidded across the snow come out cleaner and less damaged than those being skidded across dirt.

Stumps vs. Logs

All of our mushrooms will grow well on tree stumps, but maitake and reishi prefer stumps. This is not to say they will only grow on stumps - but they will fruit better on a log that is partially buried - a "simulated stump". This is probably related to the higher and more constant moisture levels that come with being in contact with soil. But remember that contact with the soil is also a vector for contaminants. So our recommendation for these species is to keep the logs above ground, and properly watered, while they are being colonized by your mushroom, and then to bury the bottom of the log 6 to 18 inches deep (the longer the log the deeper it must be buried to prevent tipping over).


If the weather has been hot and dry, and the logs have been drying out, water them or soak them before inoculating.

Inoculation holes should be 5/16 inches (79 mm) wide and about 1.25 inches (3 cm) deep. Spacing between holes should be about 6 to 8 inches apart along the length of the log, and about 2 inches apart around the circumference of the log. (see diagram) This spacing is because the mycelium grows faster parallel to the wood grain than against the wood grain. It is tempting to space plugs farther apart to make the spawn go farther, and you may have success doing this, but keep in mind that this would extend the time until first fruiting, and would increase the chance that a competing fungus would become established. Insert 1 plug into each hole so that it is flush with the inner bark. Tap them with a rubber hammer to make them go in. Cover each hole and the log ends with melted wax - this creates a moisture-tight seal so the mycelium doesn't dry out; if you are conducting your inoculations on wet logs you will need to let the log surface dry before applying the hot wax. Cheese wax and beeswax work well for this purpose because they have low melting points and can be purchased in quantity.

Care and Feeding

Your logs need to remain slightly moist, so keep them in the shade and water them if they haven't been rained on for over a week or two.

To induce fruiting

The two primary factors that affect the timing of fruiting are temperature and moisture; temperature signals the appropriate season for fruiting, and moisture is necessary for the mycelium to produce a substantial fruiting body. If you expose your logs to the weather and help them through droughts, they will eventually fruit when conditions are right, but many species can be forced into fruiting after they have colonized a log by soaking them in a cool water bath overnight.