Sawdust Spawn Use Instructions

You have just received your order of sawdust spawn. Please examine it carefully. The bag should be completely sealed. The spawn itself should be a relatively uniform mixture of brownish sawdust with whitish mycelium growing through it. There should be no green, grey, black or other unusual areas on the spawn. The spawn you have received is at its peak for use as an inoculant. If you do not intend to use it within the next 10 days refrigerate it at 2-50C. The spawn will keep for a few months, however immediate use is recommended because as the spawn matures/ages it becomes more and ‘bound’ by the mycelial hyphae. Cold temperature will inhibit the development of the mycelial hyphae. When the hyphal development progresses too far it can be difficult to break the spawn apart so that it is loose and friable and with a small enough particle size to work your inoculation tool and to insert the spawn into the holes in your logs. We recommend that the spawn be used as soon as possible – within 5 days of receipt is best. However, if the spawn has been stored refrigerated, bring it to room temperature for a few days before using it.

Handle the spawn in order to minimize exposure to ubiquitous contaminants such as bacteria and especially mold spores and to prevent dehydration. Use the following rules to protect the spawn:
• before opening, rinse bag in a dilute bleach solution and carry the bag to your inoculation site in a clean bucket;
• wash your hands and periodically rinse tools coming in contact with the spawn in the bleach solution;
• before opening and immediately before inoculation gently break the spawn up through the bag by manipulating the bag with your fingers; you can also shake/agitate the bag so spawn is loose and friable; the ‘grain’ size of the spawn should be quite small and it should break up fairly easily and not form clumps that are difficult to break apart; it should be moist but not wet
• while inoculating remove spawn from the bag in small batches as you use it, perhaps in a clean plastic container, and keep the bag closed after each removal to limit the amount of time the bag is open;
• keep the bag of spawn in a cool, shaded spot;
• schedule inoculation sessions in order to allow enough time to completely use the spawn in a particular bag in a single session;
• never put any spawn back in the bag for use later.

This spawn is used to inoculate hardwood logs that were cut in the winter and have rested for at least 1 month. It can also be used on freshly cut / recently cut hardwood stumps. You need a drill with a 12.5 or 13.5 mm (or ½ inch) bit and an inoculation tool. A depth stop on the drill bit is helpful. Drill holes to a depth of 1 and 1/8th inches or 28.5 mm. The holes MUST be sealed with cheese or bees wax or with a Styrofoam tab because the small amount of spawn in each hole can dry out in a matter of hours. For Shiitake or Oyster, drill your holes 10-15 cm (4-6 inches) apart, in ‘offset’ rows that are 5 – 7.5 cm (2 – 3 inches) apart. The holes should form a diamond pattern as in the diagram below.

o                      o                      o                      o                      o                      o                      o         

            o                      o                      o                      o                      o                      o

o                              o                              o                              o                              o                              o                              o


Fill holes with loose sawdust spawn using an inoculation tool.  For tool descriptions and pricing see our mushroom growing equipment page.

You can also use a small funnel and tamping rod to insert the spawn into the holes but a tool will speed your work.  Holes must be sealed with cheese or bees wax.  Or you can seal holes with Styrofoam caps on holes that have been drilled with a 13.5mm bit.  If you are using wax you may have to heat wax ‘in the field’.  You can use a coleman camp stove or a burner with a butane cylinder; use a tine can other metal vessel in which to heat wax.  Apply wax with dobbers or with very small sponge paint brushes or with a turkey baster.  Always use safety precautions when using gas/butane burners.  Styrofoam caps come in rolls and fit 13.5mm diameter holes.  See the above page for pricing of wax and caps.

Following inoculation, stack your logs in a shaded area And see also

The ideal location for your logs is under the forest canopy in a well-drained area with good air movement. You will need access to water unless you plan to rely on natural rainfall to provoke ‘fruiting’. For the first 4 weeks of the spawn run it is recommended that you water the logs once a week unless there is sufficient rainfall and/or the logs were quite wet (inside) when inoculated. The objective during the spawn run is to keep the moisture level inside the logs high but allow the outside to dry so as not to rot the bark off. Logs should not be exposed to full sun during the spawn run. During winter months keep logs shaded. Even if logs are under the forest canopy they may need to be covered with shade cloth or with some form of breathable covering so that they are not exposed to full/direct sun for hours at a time, especially during the late afternoon.

The logs will “fruit” 6 months to 1 year following inoculation depending on factors such as when logs were cut, how hard the wood is, how moist the sapwood is, and temperature and rainfall patterns during the spawn run. Fruiting generally starts the spring following inoculation (1 year later). Once logs begin fruiting they must be stood on end to allow the mushrooms to form and to facilitate harvesting.
Please see LOG MANAGEMENT SHEET for long-term log management.

The following books contain vital, detailed information on inoculation and log management. The techniques described are applicable, with modifications, for growing other species of wood mushrooms such as Tree oyster, Maitake, and Reishi.
Growing Shiitake Mushrooms in a Continental Climate by Kozak, M.& J.Krawcyk
Shiitake Grower’s Handbook (indoor and outdoor cultivation) by Przybylowicz,P. & J.Donaghue

These books may no longer be in print or may be difficult to obtain, and are quite expensive. An excellent source for updated and detailed information about mushroom cultivation outdoors on hardwood logs is the Cornell University website. Here is the link to their interactive website with information about log inoculation and management:

The website has videos and a 56 page manual titled “Best Management Practices for Log-based Shiitake Cultivation in the Northeastern United States” that you can browse and download for free.

In order to download the manual to your computer you will need Adobe Acrobat software. It is worth the time to check out this website even if it requires some trouble to get access to the internet. If you don’t have regular access to the internet you can print the manual (56 pages).