Spawn is usually the vegetative mycelium of the mushroom species you want to grow. It is the form in which the mushroom can be transferred to the growing medium or substrate. We produce sawdust and grain spawn for many species mushrooms.
The substrate is the growing medium to which the spawn is transferred for mushroom fruiting. Depending on the substrate, some preparation may be necessary to optimize it for growing a particular mushroom. For example: when growing on outdoors on logs, recently felled live dormant tree wood is best, when growing on straw, pasteurization or fermentation to reduce competitive organisms gives advantage to the cultivated variety.
Colonizing the substrate with vegetative mycelium after inoculation with the spawn is the first stage. This spawn run through the substrate is necessary for the mycelium to gain enough energy and mojo for the mushrooms to form. During the spawn run it is important to keep the substrate from drying out and in some cases to maintain temperature for optimal growth.
Once the mycelium has colonized the substrate this can be indicated by mushrooms forming on logs, or particular time period certain species- conditions can be changed for fruiting mushrooms. For shiitake logs, soaking in cool water stimulates mushrooms to form; for some oysters on straw changing the temperature will promote fruiting.
For more information about particular methods visit see the Woodland Mushrooms, Garden Mushrooms, and Indoor Mushrooms sections below.
Log cultivation is one of the easiest ways to get started growing woodland mushrooms. There are several considerations to optimize this process:
Logs cut from live dormant trees provide the best nutrition for the fungi because more sugars are stored in the wood for the winter. But, don’t let a windfall go to waste, leafy wood will also grow mushrooms. There is still plenty for the mushroom mycelium to consume. Choose species depending on the mushroom you want to grow.
For shiitake, oaks are generally considered optimal but maple and sweetgum work too.
Oyster mushrooms grow well on tulip poplar and some of the local strains make beautiful mushrooms on Tree of Heaven (Ailanthus altissima).
For optimal mushroom production, select healthy live dormant trees. Cut branches or trunks ranging in diameter from 3-8 inches to a manageable length. To inoculate logs, drill holes in a diamond pattern approximately 6-8 inches along the length of the log and 1-2 inches around the diameter. The fungus grows more rapidly along the grain of the wood than across it. This diamond pattern allows the different inoculation points to grow together more rapidly and coalesce into a single mycelium that reduces the likelihood of contamination and matures more quickly so mushrooms can be fruited.
Plug the holes with spawn and cover them with wax to prevent the spawn from drying out and seal out possible contaminants. Any wax will work but food grade cheese wax adheres well to the log and remains pliable in cold weather. Label the log with the strain, the date, and the wood species so you can keep track of what you did in three or four years. The log is then ready to be stacked in the laying yard for the spawn run. The object of the spawn run is to decay the wood so select a shady humid spot where things rot. Maintaining log moisture content is the most important management objective for the next 6-12 months during the spawn run. The majority of the labor is finished, now a little patience and benign neglect while the mycelium matures…
If you have inoculated your logs in winter or early spring, by late summer you should notice white zones of mycelial growth on the ends of the log that coincide with inoculation sites. Check these logs after rains and once you notice a few mushrooms forming naturally they are ready to be put into production. Shiitake logs need soaking for about 24 hours to initiate mushroom formation. A natural water source is best, such as a well, pond or stream. If you use chlorinated water from a municipal source make sure to let it stand for a day or so for the chlorine to evaporate, as this will kill mycelium it comes into contact with. After soaking, lean or stack the logs so there is good air flow around them and in several days or sooner you should see primordia forming.
Harvest the mushrooms at the largest size to which they grow while the cap margin is still in-rolled. If you harvest when the cap margin has flared out, you may harvest more weight but the firmness and shelf life is reduced. The right time to harvest is a balance between many factors including your time, marketing goals, the weather, insect pressure, etc. When harvesting use a knife to cut the stem from the log to prevent damage to the log bark. I use large paper bags for collecting, but baskets and boxes work well, too. Do not store mushrooms in plastic, this promotes anaerobic conditions and things can get slimy quickly
After shiitake mushrooms are harvested from the logs, there needs to be a 6-8 week rest period so the mycelium can regain its mojo. If you push the logs sooner, they will wear out and long term yield will suffer. If you manage your logs well, you will be able to harvest mushrooms for several years.
Managing Oyster mushroom logs: Maintaining log moisture content is critical to ensure the fungus survives and produces mushrooms. Sections of the log dry out rapidly when the bark is damaged, so use caution when handling the log. Choose a shady, humid spot in your garden that you pass by frequently as the harvest window for excellent mushrooms is short and you want to beat the critters and insects to them. Place the log in contact with the ground. Do this by laying it horizontally directly on the ground, or use it to retain a garden bed or walking path that has shade cover. Or install the log as a totem. Bury the log vertically one-third of the length into the ground. With either method, as the fungus grows it will be able to translocate water from the ground. If there are extended dry periods, water the log as you water your garden.
In the fall and perhaps in the spring, look for mushrooms after rainy days. The caps usually grow in clusters and are grey to brown in color. Use a knife to cut the caps away from the log taking care to minimize damage to the bark. Use the mushrooms fresh in your favorite recipe or dry them and store them for future
An alternative to drilling holes is cutting the log into discs or cutting wedges out of the log and packing spawn in and “reassembling” the log with nails. This is a fast way to inoculate oyster mushrooms to large logs or stumps. Wrap the newly inoculated log with plastic bag or sheet until the fungus establishes in the log (6 weeks or so) to prevent drying. the logs can be partially buried horizontally and used as a garden bed retainer or vertically as a totem.
Another log cultivation method is the log raft which will also work for oysters, maitake, reishi, Pholiota nameko, and Hypholoma sublateritium. A log raft is built by laying logs side-by-side, scoring them and packing spawn into the space between and covering with wood chips.
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Mushrooms can be cultivated in many microclimates a diverse garden provides. There are a couple of species that are very easy to cultivate. The Garden Giant (Stropharia rugoso-annulata) in woodchips and straw mulch and the Almond Portobello (Agaricus subrufescens) in compost. We’ll have more information about growing these and other species as this site develops. If you are interested in learning more about growing mushrooms in the garden, Sharondale offers hands-on workshops.
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