Sweet chestnut

Value to bees

Nectar

High

Pollen

Very high

As a honey crop

Major honey crop — yields a surplus in good years

Which bees, and why

The catkins are worked heavily by honey bees and by a wide range of flies and beetles. The strong, faintly unpleasant scent of chestnut in flower is a genuine insect-attraction strategy rather than an accident, and it is noticeable from some distance.

Nectar and pollen are fully exposed on the catkin, so access is universal — no corolla tube to exclude short-tongued insects.

Worth knowing

An exceptional pollen source — the catkins shed enormous quantities — and a good nectar source in the right weather. The pollen arrives at a useful moment for colonies building towards late summer.

Flowering

In flower

June to July (northern hemisphere)

Two to three weeks at a given site, later at altitude. It arrives in the gap after the spring flows and before the late summer ones, which is part of its value to beekeepers.

When nectar flows

Nectar secretion needs warmth and humidity together. A hot dry spell during flowering suppresses the flow badly, which is why chestnut honey yields swing so hard between years.

Year-to-year variation

Substantial in a good year across the chestnut regions of Italy, France, Spain and the Balkans, and close to nothing in a dry one. Chestnut blight and ink disease have also reduced the standing resource significantly over the last century.

What it does to the honey

Chestnut nectar carries the tannins and phenolic compounds that make chestnut honey bitter, dark and long-finishing. It is the clearest European case of a honey that is prized precisely for a quality — bitterness — that a general audience would call a fault, and the bitterness is the tree's chemistry arriving essentially intact.

Growing it

Conditions

Deep, well-drained, acid to neutral soil and a warm summer. It dislikes chalk and shallow soils, and needs more heat than northern Britain reliably provides to set good nuts.

Size

20-35 m; individual trees can live over five hundred years.

Native range

Southeastern Europe and Asia Minor, spread across western Europe in antiquity — largely by the Romans — and now naturalised well beyond its original range.

Suits

Large gardens, Orchard

• Far too large for a small garden — this is a parkland and woodland tree, and a mature specimen will shade out everything under it.
• Coppiced sweet chestnut, still widely managed in southern England for fencing, flowers very little: the cut cycle removes the mature wood that would otherwise bear catkins.

What it looks like

A broad, deeply furrowed-barked tree with long glossy toothed leaves, and conspicuous pale yellow-green catkins up to 25 cm long in midsummer. Old trees develop a characteristic spiral twist in the bark.