Three days after a good soaking, the forest floor answers. Here's the mechanism, and why foragers watch the forecast like sailors watch the sky.

Water wakes the mycelium

The mushroom you pick is just the fruit. The real organism — a web of mycelium under the soil — waits through the dry weeks, and rain is the signal to push up fruit.

Warmth decides how fast

Rain alone isn't enough; the ground has to hold some warmth. That's why a summer downpour fruits in days, while a cold autumn rain fruits in a week.

Read the rhythm

Soak, then warmth, then walk. Learn your local rhythm and you'll stop guessing and start knowing — which is the whole craft.