Slippery jacks in autumn, the season's second wave

Many foragers consider autumn the best season for slippery jacks. Summer flushes are explosive but short-lived, while in autumn the slippery jack (Suillus luteus and its close relatives) gives a plentiful, long-lasting and remarkably clean harvest.

Cool nights, gentle rains and warm soil create almost ideal conditions for it. Let's look at why autumn slippery jacks beat summer ones, where to find them and when the season finally ends.

Why slippery jacks love autumn

In summer, the slippery jack's main enemies are heat, which dries out the sandy soil, and maggots, which quickly spoil the mushrooms. In autumn, both problems recede.

Cool nights hold back the maggot invasion, so autumn slippery jacks are much cleaner. Rains become more frequent and more even, and the soil, warmed over the summer, holds its heat for a long time. With this combination, the mycelium fruits eagerly and generously.

That's why the autumn flush of the slippery jack is often called the main one of the season: there are lots of mushrooms, they're firm, and picking them is a pleasure.

Why autumn slippery jacks beat summer ones

You can see the difference right in your basket.

• Cleanliness. Autumn slippery jacks are less infested with maggots, because the cold holds insects back.
• Firmness. In cool weather the mushrooms grow more slowly, so the flesh is denser and holds its shape better.
• Longer flushes. Autumn mushrooms stay fresh in the ground longer, so you don't have to rush.
• Abundance. The main flush of the harvest often falls in September.

That's why autumn slippery jacks are especially prized for pickling and drying: the dense flesh makes for better preserves.

Where to find autumn slippery jacks

The spots are the same as in summer, with a few small adjustments for the cold.

• young pine stands and pine plantations;
• bright, sun-warmed clearings and forest edges;
• south-facing slopes and sandy hills that hold heat longer;
• patches of mixed forest where pine grows next to birch.

In autumn, look for slippery jacks where the sun still reaches: shaded, damp hollows cool down quickly, and the mushrooms stop there sooner. On sun-warmed south-facing slopes, the season lasts longest.

In autumn, its relatives do well alongside the slippery jack too: the bovine bolete and velvet bolete, which handle the cold well.

When the season ends

The autumn flush lasts as long as the soil stays warm, usually into October, and in warm years into November. The first lasting frosts bring the season to an end.

Frost-bitten slippery jacks lose their flavor and turn watery, so after a few frosty nights they're no longer worth picking. But as long as the days are warm and the ground hasn't frozen, every new rain can still bring a flush.

To catch the last warm windows, follow the weather with our mushroom radar: it shows when moisture and warmth line up well for mushrooms to appear. In autumn this is especially useful, because good days become rarer.

Sources

• “Key to the Fungi of Ukraine” (Kyiv, Naukova Dumka publishers).
• Suillus luteus on GBIF, the global biodiversity database.
• Suillus on MycoBank, the international fungal nomenclature database.
• Suillus luteus on Wikipedia.