Drill the Holes

Making doorways for the fungus

Right now your log is solid wood, sealed under bark. The shiitake mycelium cannot get inside on its own. So we drill a pattern of small holes all over the log. Each hole becomes a doorway where we will later place the spawn. From those doorways, the mycelium spreads out through the whole log.

Drilling uses a power drill, which is a sharp, fast, adult-only tool. Your job is just as important, though: you are the designer of the pattern. Getting the spacing right is what makes the mycelium spread evenly.

The right hole

For plug spawn — the little colonised dowels we use next lesson — the standard bit is 5/16 inch (about 8.5 mm) wide. Each hole is drilled about 1 inch deep, just past the bark and into the pale wood underneath.

Why that exact size? The hole must be a snug fit. A dowel that is loose will dry out; a hole too small will not take the dowel at all. Matching the bit to the spawn is the trick.

The diamond pattern

Here is the part you plan. Holes are not drilled randomly. They go in neat rows running along the log:

• Space the holes about 4 to 6 inches apart down each row.

• Turn the log a little and drill the next row about 2 to 3 inches over.

• Offset each row so the holes sit between the ones next door.

Look down the log and the holes make a diamond shape. This spacing is not fussiness — it lets the mycelium from every hole reach and join up, so no part of the log is left uncolonised. A 3 to 4 foot log usually needs around 50 holes in total.

Measure, mark, count

Before the drill even switches on, this is where you shine:

1. Use a ruler or tape to mark hole spots with chalk or a crayon.

2. Count your marks — aim for about 50 on a full log.

3. Check the rows go all the way around, so the whole surface is covered.

Then the adult drills each marked spot to the right depth while you count them off and keep track.

Safety check: while the drill is running, keep hands and hair well clear, and let the adult control the tool. You are the measurer and the counter, not the driller.

With a neat diamond of clean holes ready, your log is prepared. Next comes the best part — hammering in the living spawn.