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A Prize Worth a Few Prickles

Autumn in a British wood offers many gifts, but few are as satisfying as the sweet chestnut. Walk beneath a mature Castanea sativa after a windy night in late September and you will find the ground strewn with spiky green husks that split open like hedgehogs yawning, each one revealing two or three glossy mahogany nuts inside. Get there early and you will have the pick of the crop; leave it a day and the squirrels, jays and deer will have done their rounds.

Sweet chestnuts are one of the few wild foods that genuinely fills you up. They are starchy rather than oily, low in fat and rich in complex carbohydrates — the reason they were once ground into flour and used as a staple in parts of southern Europe. In Britain they grow best on the lighter, acidic soils of the south and west, often in old parkland, estate woods, churchyards and along ancient lanes where the Romans and later planters left them behind. Learn to spot them properly and you will have a free, generous harvest every October.

Sweet Chestnut or Conker? Getting Identification Right

This is the single most important thing to get straight, because the two trees are often confused and the horse chestnut is not food.

• Leaves: sweet chestnut leaves are long, glossy and lance-shaped with a deeply serrated, almost saw-blade edge. Horse chestnut leaves are palmate — five to seven leaflets radiating from one stalk, like an open hand.
• Husks: sweet chestnut husks are densely covered in fine, needle-sharp spines and go from green to brown as they ripen, splitting into four valves. Conker cases are thick, leathery and far less spiky, with scattered blunt warts.
• Nuts: sweet chestnuts are flat on one side with a pointed tip and a small tuft, and they are often two or three to a husk. Conkers are round, shiny and smooth, with a pale circular scar, usually one to a case.

If you are in any doubt at all, leave it. Take a good field guide, and if possible go out the first time with someone who already knows the tree.

Where and When to Look

The season runs from late September to early November, and the trigger is simple: husks splitting and falling. The first good gale after a warm, dry September will bring down a carpet of them. Chestnut trees produce heavy crops in some years and light ones in others, so a favourite spot can be barren one autumn and groaning the next.

Look for tall, broad-crowned trees with distinctive spiralling bark on older trunks — the ridges often twist to the left. They favour well-drained, slightly acid ground, so you will find them more often in the south, the Welsh borders, the Marches, and old landscaped parks than on chalk or heavy clay. Remember that all land belongs to somebody: public footpaths give you a right to pass, not to pick, so seek permission on private estates, check local byelaws on commons and nature reserves, and never strip a site bare. Take a share and leave plenty for the wildlife that depends on this crop to see out the winter.

Gathering, Sorting and Storing

Only ever collect nuts from the ground, never shake or break branches. A few practical bits of kit make the job far more enjoyable:

• Thick gardening gloves for prising open husks — the spines are unforgiving.
• A wicker basket or cotton bag rather than a plastic carrier, which makes the nuts sweat and go mouldy within days.
• A stick for raking through leaf litter, and a small knife for checking the odd suspect nut.

Back home, tip the haul onto a tray and sort ruthlessly. Discard any nut with a tiny round hole — that is the exit of a chestnut weevil — along with anything soft, damp or already sprouting. Then do the float test: drop the nuts into a bowl of cold water. Sound nuts sink; the hollow, grub-ridden or shrivelled ones float, and they go straight to the compost. Dry the keepers on a cloth for a day or two, then store them in the shell in a cool, airy, frost-free place. They will keep for a few weeks. For longer storage, blanch and freeze them whole, or make a purée and freeze that.

Roasting, Boiling and Peeling

Raw sweet chestnuts are bitter and hard on the digestion, so always cook them. The classic method is roasting, and the golden rule is to score first: cut a shallow cross or a long slit through the flat side of each shell so the steam can escape. An unscored chestnut in a hot oven will explode with real force. Roast at around 200°C for twenty to twenty-five minutes until the shells curl back. Tip them into a tea towel, wrap and rub — the inner skin comes away far more easily while they are hot.

For soups and purées, boiling is easier. Simmer scored nuts in water for fifteen to twenty minutes, then peel while warm. Alternatively, roast or boil and then push the flesh through a sieve or blitz it with a little stock for a smooth, velvety purée. Whatever you do, work quickly: chestnuts turn crumbly and stubborn once cold.

Cookery for a Glut

Chestnut purée loosened with vegetable stock, a splash of cream and a grating of nutmeg makes a deeply comforting autumn soup, especially with a handful of fried wild mushrooms stirred through at the end. For a stuffing, soften onion and celery, add sausage meat, breadcrumbs, chopped sage and a good quantity of roughly broken roasted chestnuts, then bake in the bird or in a dish. They are also excellent tossed into a pan with Brussels sprouts, bacon and butter, or folded into a simple cake with dark chocolate.

Any nuts left over can be dried slowly in a cool oven and ground into flour for thickening stews. And if you find far more than you can use, share them — a bag of hand-gathered chestnuts is one of the finest thank-yous a forager can give.