How do you incubate mushroom logs?

Before you can get to the wonderful stage of harvesting your gourmet mushrooms, you must first put in the work required for your best logs to fruit. This entails inoculating and incubating the mushroom logs with mushroom spawn. A mushroom log can produce mushrooms for up to four years if properly inoculated and incubated. Oak logs can produce mushrooms for up to seven years.

How to Inoculate Your Mushroom Logs

Ideally, start inoculating your logs in winter or spring. Place your logs in a shaded area to avoid exposing the spawn to sunlight and to reduce the loss of moisture from your logs.

If the moisture content in your logs is above 35%, wait for them to dry up before using them. Alternatively, if the moisture level is below 35%, water them before inoculating them.

Inoculation Procedure

While you can handle this undertaking independently, it is best to get help as some hard labor is involved. Get at least two other people to assist you as you need help drilling logs, inserting spawn, and moving the logs to their final destination.

Items Required

• Drill 
• Bits and stop collars
• Worktable or a sawbuck
• Measuring tape
• Rubber Hammer 
• Inoculation tool 
• Paraffin/cheese wax/plastic foam and wax warmer
• Wax dropper or brush 
• Rubbing alcohol

Inoculation Instructions

1. Ensure the logs are dirt-free and other contaminants before working on them. You can clean them using a brush with hard bristle to dislodge any dirt stuck in the log’s bark.
2. Secure your logs using a saw busk before drilling to avoid hurting yourself. Then dip your drill bit in alcohol to sterilize it before you start drilling. And after drilling each hole to avoid getting any bacteria or fungus into the subsequent holes.
3. Drill the holes 3-4 inches apart and make the space between the rows of holes 3 inches apart. Remember, some spawns, such as shiitake mushrooms, spread poorly across the wood grain, so drilling holes closer together will improve colonization.
4. Stagger the location of the holes so all the holes in the log are not parallel. Strive to create diamond patterns while drilling holes.
5. Most spawn suppliers will give the exact depth of the holes you should drill. But as a general rule of thumb, drill holes 1¼ inches deep and between ¼ and ½ inches in diameter.
6. Insert the spawn into the drilled holes immediately to prevent moisture loss or entry of contaminants into the log. 
7. Ensure your hands are sterilized before handling the mushroom spawn. 
8. Place your dowel spawn into a drilled hole and use the hammer to push it into the hole gently. Hold the span with forceps to avoid injuring your fingers while hammering.
9. Insert the spawn while the sawbuck holds the log in place. 
10. For the sawdust spawn, use the inoculation tool to insert the spawn into the drilled holes. Pack each hole with as much spawn as possible to increase colonization chances. 
11. If unsure how to do the spawning, follow the spawn manufacturer’s manual.
12. Then seal the holes with paraffin or cheese wax. This will prevent moisture loss and prevent contamination of the spawn. 
13. Do not overheat the wax, as this will compromise its ability to create a proper seal due to the breakdown of wax molecules. Use the wax dropper or brush to apply the wax.  
14. You can also wax the log ends, but it is unnecessary. It helps to prevent moisture loss from the logs.

Key Notes

• Keep records of your inoculation to ensure you can repeat the same inoculation process if you get successful results. Also, note down the specific strain of spawn you used and other important details.
• Use a moisture meter to keep track of the moisture levels in the logs. But you will need to figure out the moisture levels of the logs based on the type of tree used, as moisture meters are not 100% reliable.
• Label the logs with the inoculation date and the mushroom spawn strain for easy progress tracking.

How to Incubate Your Mushroom Logs

Follow these steps to incubate them. Incubation is the process of letting the mycelium develops inside the log. This is the process of spawn colonization, where it spreads throughout the wood grain before the log can start fruiting and producing mushrooms.

Incubation Instructions

1. Pile up the inoculated logs and cover them in plastic or a burlap fabric to allow rain to moisten them.
2. Ensure the logs are in a shaded area with low wind exposure. Place them on a pallet or poles off the ground but not too high off the ground. Placing them on the ground may lead to rotting due to excess moisture.
3. Ensure they can still receive rainfall as they need moisture as they incubate.
4. Keep checking the moisture levels and watering the logs to avoid drying up, as this will prevent successful colonization of the logs. 
5. The logs should receive until 1” of weekly rainfall to maintain their moisture levels. If there is no rainfall, water the logs manually with a hose. 

To incubate your log indoors;

1. Store them in a room with temperatures ranging from 48-75⁰ F with medium to high humidity. Keep them away from direct sunlight. Ensure there are no fans or heaters, or wood stoves, as these will dry the logs up. 
2. Ensure the logs get a natural light and dark cycle similar to the day and night cycle they would get if they were outside. 
3. Do not store them in a cold garage or basement, as the excess moisture may lead to rotting. They will also not get enough light which is needed for successful incubation.