How to Grow Shiitake Mushrooms on Logs #MushroomMonday

by: EJ on 04/25/2016

We are sticking with the growing mushroom theme this week for #MushroomMonday.  In this excerpt from Mycelial Mayhem: Growing Mushrooms for Fun, Profit and Companion Planting, David and Kristin Sewak explain the basics of growing shiitake mushrooms by inoculating logs using a “drill and fill” method. 

Shiitake mushrooms on log

Shiitake mushrooms on log

There are many ways to get shiitake spawn into a log. We will name and explain a few, but we’ll focus on the one method we found to be best overall, in terms of production, time, ease, and labor. You can take a chainsaw, cut out a wedge, pack with spawn, and replace the wedge, anchoring it with nails or screws. This may be the oldest method, but we found the spawn dried out, bugs would bore in and eat the mycelium, and native mushrooms would colonize parts of the log, creating competition. We have also tried rope spawn with shiitake, but it never bore fruit for us. We found that the rope method works better with an aggressive species like oyster.

The most common method for growing shiitake mushrooms and the one we had the most success with is drill and fill. This is where you drill holes and then fill them with sawdust spawn, plugs (small dowels covered in mycelium), or pre-designed plugs with a Styrofoam cap, called a “thimble.” We have used all three of the available spawn types and found sawdust spawn to be the most economical and successful, followed by the dowels, and finally the Styrofoam-capped ones (they had a tendency to lose their caps over time, drying out the spawn). The dowels are effective, and we have used them successfully with other species. But when inoculating 200+ logs a year, we found the sawdust to produce the best and be the most economical.

A higher speed drill works best, and your drill bit needs to match the method you are using. The best bit we found was one that has a stop collar on it that matched up in diameter with the  inoculating tool. The stop collar ensures that you drill to the right depth each time, so that you don’t have to guess how deep to go. Though there are a lot of different drilling patterns out there, we found that a diamond-shaped pattern was the easiest to lay out and drill. It also had great spawn run success. If you are looking to knock out a bunch of logs, the diamond pattern is the way to go. We also did a spiral pattern, and when the log fruited, it was very unique looking. We would do a couple of patterns that became mushroom art, which were used as eye catchers at shows. When you work hard, you should also have some fun. So, even though 99 percent of our logs were straight, diamond-patterned production logs, we also had a small collection of weirdly shaped logs with short branches and different inoculation patterns, but these were just for show.


• Shiitake spawn: sawdust, plug, or thimble

• Oak or other appropriate hardwood logs — approximately 4' in length × 3"–10" in diameter

• Tree marking crayon (or sidewalk chalk)

• Tape measure with metal claw on the end

• Drill and drill bit

• Inoculating tool (for sawdust spawn)

• Wax (not needed if using thimble spawn)

• Wax bowl (not needed if using thimble spawn)

• Wax daubers (not needed if using thimble spawn)

• Equipment to heat the wax, such as a propane stove or turkey fryer (not needed if using thimble spawn)

• A surface suitable for drilling logs (two saw horses with boards to place logs on)

• Aluminum log labels and ballpoint pen

• Heavy-duty staple gun

• Pallets

• Pine mulch (optimal, if your yard is in a hardwood forest)



1 Place a log on your work station.

2 Take the tape measure and marking crayon to lay out your diamond drilling pattern. (After stealing our kids’ sidewalk chalk, Dave discovered that tree marking pens, merely oversized crayons, work best and are relatively inexpensive. Plus the kids don’t get upset that their favorite color of chalk is gone. These can be found where chainsaws and similar equipment are found.)

3 Stretch the tape the length of the log, securing the claw at the far end.

4 Down the length of the log, mark the first row of hole locations with your crayon, about 6" to 8" apart. Once you have figured how aggressive your strain is, or you are drilling and filling other species, you can tighten this measurement or widen it out.

Studen marking drill holes

Student marking drill holes

5 Once you have your first row laid out, pick two holes on either end of the log, put your tape measure dead center and measure 2" on either side of the marked holes and make a mark. Remember to mark both ends of the log and on either side of the existing row. Rotate your log and lay your tape on the marks you made. You will again be making marks every 6" to 8", but you will want them to be made 2" off the original row, and dead center between the existing holes. When you repeat this on the side, you will see the diamond coming into form. You will continue to rotate and mark holes in this alternating pattern around the log. If you have a branch coming out or some kind of anomaly, you can add an additional hole or two. We would also add a hole or two around the ends, but we would never put a hole less than an inch from the edge of the log.

Student drilling holes

Student drilling holes

6 Drill holes in the log at each mark, ensuring that you have the right depth each time (the same depth as your inoculating tool). Approximate Hole Spacing for Various Species: Hericium — 4"; Reishi and Nameko — 6"; Shiitake — 6" to 8"; Oyster — 10"

Student filling holes with spawn

Student filling holes with spawn

7 After you have created holes around and up and down your logs, you are ready to insert the spawn into the log. If you are using an inoculating tool, you simply pack as much spawn into the tool’s cavity as you can, place over the hole and push down with your thumb, or smack it with

your palm. This will push a plug of spawn into the hole. You will repeat this process until all of your holes are filled with spawn.

Dipping the dauber in hot wax

Dipping the dauber in hot wax

8 After you have the holes filled with spawn, double check to make sure you have them all filled. When you first start, do a “finger test,” pushing down on the spawn with your finger. Next, you will seal the hole with wax. There are a number of kinds of wax and ways to apply it. When we were hobbyists, we used tub wax, a soft wax you pinch and place over the hole and press down with your thumb. This wax works ok, but it is messy and when it gets warm in the summer, we found the wax would stick to our clothes and hands when we were moving logs around. Cheese wax became our standard, which needs to be melted and applied over each hole with some sort of instrument that is dipped in the hot wax. Be careful, as this wax can catch on fire! For  application, we found that wax daubers, little cotton balls on a piece of twisted wire, work the best and are fairly cheap. You can purchase these at mushroom spawn suppliers. You simply dip the cotton end in your melted wax, and then just dab wax over your holes.

9 After you have covered your inoculation sites with wax, double check you have covered them all and that they are completely covered with wax. Sometimes you will see a little spawn peeking out, so you will need to apply more until the spawn is completely covered. An opening to the spawn is an opening for creepy crawlies who eat the spawn and mycelium you worked hard to insert. You don’t want to feed anyone who hasn’t helped! Openings also invite other mushrooms to colonize the log.

10 Label each log with an aluminum tag on the end. Record the date and the strain of mushroom, etching the information with a ballpoint pen. Attach the label with a sturdy staple gun.

Labeled shiitake logs stacked in cross-hatch arrangement on pallets

Labeled shiitake logs stacked in cross-hatch arrangement on pallets

11 After you have inoculated all your logs, stack them in your pre-chosen shady area with water access. A conifer stand works best, as no competing hardwood mushrooms are present. We like to put pallets down and stack the logs on top of them. First, we add pine chips under the pallet to help cut down on native hardwood fungus attacking the logs. When you stack your logs, lay down a row, leaving space between the logs for air circulation. Place each successive row perpendicular to the last one so that when finished, your stack is cross-hatched. Try to place like-diameter logs together if you have a mix of sizes. Place larger diameter logs on the ends and smaller ones in the middle to help with air circulation. Usually each row had between 4 and 7 logs, depending on diameter. You can stack them as high as you want, but we like to keep our stacks between 4 and 6 rows high. This way we can look into the stack and see if any primordia (mushroom pinning) is occurring.

12 You will want to stand your logs up when it is fruiting time because big stacks can be cumbersome to harvest from. You can lean logs against almost any kind of structure, like a shed or trees, or you can construct custom log stands from lumber.

13 Remember to keep your logs moist when they are fruiting. Mist them at night if there is no rain in the forecast. An hour of misting is usually sufficient. When we inoculated in the dead of winter, we would bring those logs indoors, keeping them in our basement for a couple of weeks or until the outside temp was above freezing. This helps speed up your spawn run. Just remember that houses can get very dry in winter. Make sure you keep your humidity up if you are going to do this.


For more information about growing, harvesting and selling mushrooms, order your copy of Mycelial Mayhem



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