We're used to seeing the dried variety at Christmas, but Annie Bell reckons that the wet one's time has come

"Wet walnuts? What on earth are those?" asked Martin Parsons, one of the few professional walnut picklers in the British Isles. As the leaves on the trees begin to turn and the nuts start to fall, their casings cracked and blackened, from the trees around his home Womersley Hall in Yorkshire, he claims never to have heard of them. "You mean fresh walnuts?" Yes, that is exactly what I mean.

Describing walnuts fresh from the tree as wet is not completely wide of the mark. They're not dripping, but distinctly damp outside and in. It makes them deliciously creamy to the bite as opposed to brittle like the kiln-dried nuts that grace the sideboard at Christmas and make their way into cakes. In fact, those who find the dried variety too bitter might be converted by the fresh and wild type.

They are that much more fragrant and pure in flavour than the often old and musty-tasting dried nuts. And instead of having to wrestle them from their shell with a nut cracker, they can be persuaded open with a gentle thud from the end of a rolling pin on a board. A lunch of wet walnuts and a mature farmhouse Cheddar is a rare seasonal treat.

Walnuts have two lives in any one year. Towards the end of June or beginning of July they can be picked and pickled. At this time they are little larger than a 50-pence piece and the nut and shell have yet to form inside the soft outer casing (the age-old test for readiness being to insert a knitting needle). This relatively lengthy procedure involves top, tailing and pricking them, before immersing them in brine until they turn a dark olive in colour.

They are then drained and dried in the sun for three to four days until they start to shrivel (which given the nature of our weather just might explain why we don't find more commercial picklers) before being bottled in vinegar with spices. In short, it's easier to buy them.

Wet walnuts are a different matter. Arriving at the point when Kentish cobnuts are tailing off in October, they are a well-timed harvest and this year more than most. It has been a disastrous year for cobs with some Kentish growers reporting a total failure of their crop. A Kentish cob is a type of hazelnut, though larger and longer, and there are various types, all cultivated to be eaten green and fresh. If you missed them when they were pale and verdant at the beginning of the season (traditionally commencing on St Philibert's Day on August 22), don't despair. What late-season nuts you can lay your hands on, by now brown in husk and nutty, can be stored in a tin in a cool place for weeks to come.

As for wet walnuts, you may be lucky enough to find them at the greengrocer (supermarkets don't like the earwigs), or if you have access to a walnut tree and don't mind the tanner's hands – the outer casing stains – rootle around and collect any that have fallen. Having gathered your booty, remove the outer husk to reveal the damp walnut shell inside; the fresh nuts within are good for about two weeks. If you keep the unopened walnuts covered with a damp tea towel their life can be extended. Whatever, enjoy them while you can, they're not around for long.

Womersley Crafts and Herbs, Womersley Hall, nr Doncaster, Yorkshire (01977 620200)