The second flush of porcini: when and where to look

Experienced foragers know that porcini don't grow “a little at a time, all the time”. They come up in flushes, and between them the forest can be almost empty. The first, summer flush falls in June–July, and the most powerful one — the second — arrives at the end of summer.

Let's look at when the second porcini flush begins, why it's richer than the summer one, and where to find porcini in autumn.

What porcini “flushes” are

Mycelium doesn't fruit continuously but in bursts — whenever moisture and temperature are right. Between flushes it “rests”, which is why the forest is either full or empty. For more on why mushrooms grow in flushes, see our separate article.

Porcini have two or three distinct flushes per season:

• Summer — June–July, often cut short by heat.
• Autumn (second) — late August and September, the richest.
• Sometimes a third — in a warm October, before the first frosts.

When the second flush begins

The second flush starts when the July heat breaks: the soil still holds plenty of warmth, while cool nights and morning fog add moisture. In most regions that's late August, with the peak in September.

The trigger is rain during a cool spell. After a good August rain, porcini pop up together within a few days. To catch that moment, check the mushroom radar: it shows good windows for your region.

Why autumn porcini beat summer ones

The second flush is prized for more than just quantity.

• Fewer worms. In the cooler weeks of August–September there are fewer insects, so autumn porcini are more often clean than July ones.
• Firmer flesh. Autumn porcini are denser and hold up better when dried or pickled.
• Bigger groups. The second flush is usually more abundant, so your basket fills up faster.

We've written separately about how summer porcini differ from autumn ones — the difference isn't just in when they appear.

Where to look for porcini in autumn

Porcini grow in both conifer and deciduous forests, forming mycorrhiza with a range of trees.

• Pine forests. The pine bolete loves sandy soil under pines, often along forest edges and in clearings.
• Oak and beech woods. This is home to the summer bolete (Boletus reticulatus), also called the reticulated bolete.
• Birch woods. Boletus betulicola keeps company with birches.
• Edges of clearings and paths. Warm but not parched spots with more light.

Look for porcini where you found them last year: the mycelium lives for years, and good spots repeat.

Sources

• “Key to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishing house).
• Boletus edulis in GBIF, the Global Biodiversity Information Facility.
• Boletus edulis in MycoBank, the international fungal nomenclature database.
• Boletus edulis on Wikipedia.