Mushroom drought: why mushrooms vanish and when they come back

Every forager knows this sad time: the heat sets in, there's no rain for weeks, and the forest seems to die. No matter how long you wander, your basket stays empty. This is the mushroom drought, a period when the mycelium goes dormant and waits for moisture.

Let's look at what really happens to mushrooms during a drought, why even the first rain often doesn't help, and when it's worth heading back into the forest.

What happens to the mycelium during a drought

The mycelium, a fine lace of threads in the soil, depends heavily on moisture. When the leaf litter dries out, these threads don't die, but they switch into survival mode: they stop growing and don't form fruiting bodies.

Put simply, in the heat a mushroom has nothing to grow from and no reason to grow. All of the mycelium's energy goes into keeping itself from drying out, not into a harvest for us.

That's why, even in a forest with seemingly healthy mycelium, it's empty during a drought. The mushrooms haven't gone for good; they're just waiting for better conditions. To track when the moisture returns, use the mushroom radar.

Why the first rain after a heat wave is often useless

You'd think: it's rained, time to go mushroom hunting. But after a long drought the first rain usually brings nothing, and that's to be expected.

• The moisture goes into recovery. Parched leaf litter soaks up the first water like a sponge, and there's nothing left over for the mycelium yet.
• The mycelium needs time. Even once it has had a drink, it doesn't fruit right away; fruiting bodies take several days to form.
• One rain isn't enough. After a long heat wave you need two or three rounds of rain for the soil to get truly soaked.

So the disappointment of "it rained, but there are no mushrooms" after a drought is perfectly normal. The forest simply hasn't come back to life yet.

When the mushrooms come back

For a drought to turn into a harvest, you need two things together: steady moisture and moderate warmth. Here's roughly how the mushrooms return.

1. The first rain wets the leaf litter, but there's no harvest yet.
2. The second rain a few days later builds up a reserve of moisture in the soil.
3. Two to four days after that, the mycelium starts fruiting, and the first flush begins.

If cooler, damp weather follows the heat, the mushrooms come back in force. The first to respond are slippery jacks, followed by chanterelles and porcini.

What a forager can do during a drought

Even in the dry season, there are ways not to be left completely without mushrooms.

• Look for damp spots. In lowlands, hollows, shady mixed and deciduous forests and near water, moisture lasts longer, so the odd mushroom turns up even in the heat.
• Head out in the morning. At night the dew moistens the leaf litter, so your chances are a little better early in the morning.
• Wait for the second rain. Don't waste your energy on a trip right after the first rain; give the forest a chance to drink.
• Watch the weather as a whole. The mushroom radar takes stored moisture and warmth into account, so it will tell you when the drought is finally letting go.

And if we're talking about the hot summer months, it's also worth reading our separate article on whether to go to the forest in the heat.

Sources

• “Identification Guide to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishers).
• Boletus reticulatus on GBIF, the global biodiversity database.
• Fungi on MycoBank, the international fungal nomenclature database.
• Mushroom on Wikipedia.