How to Preserve Conkers for Crafts and Games: Storage and Care

There is a particular disappointment in opening last year's conker box in November and finding a heap of shrivelled, dusty marbles that weigh nothing at all. It happens because conkers are seeds, not pebbles. They arrive in autumn full of moisture, and everything after that is a race between drying out neatly and quietly rotting. Handled well, a good batch will keep its shape, colour and hardness for a year or more — long enough to paint, drill, thread, or save for a rematch.

Choose conkers worth the effort

Sorting is where most of the work is saved later. Pick conkers that feel heavy for their size, with a glossy, unmarked shell and no give anywhere. Put aside anything with a soft patch, a hairline crack, or a neat round hole — a hole means something has already chewed its way out, and a patch of fine sawdust-like dust near one means something may still be inside.

Gather from dry ground soon after they fall. Conkers that have lain in wet grass for a week are already going mouldy under the shell, even if they look fine. Carry them home in the husks if you can; they cushion each other. Then be ruthless at the kitchen table: fifteen good conkers are worth more than forty mediocre ones.

Clean them without soaking the life out of them

Pop off the husk and the pale cap. Most dirt comes away with a dry soft brush — an old toothbrush is ideal for the dimples. For sticky patches, use a barely damp cloth and dry the conker straight afterwards.

What to avoid is the overnight soak. Sitting in water softens the shell and pushes moisture into the cap scar, which is exactly where rot starts. The old trick of soaking conkers in vinegar, or vinegar and water, has been passed around for decades as a way to see off grubs and mould. It is a folk remedy rather than a guarantee, and a long soak does more harm than good. If you want to try it, keep it to a five-minute dip in diluted vinegar, dry them thoroughly, and check afterwards for any softening.

Dry them slowly — the part everyone rushes

Lay them in a single layer, not touching, on newspaper, a wire rack or a slatted tray. A cool, airy room out of direct sun is right; a shed or garage with decent airflow works well. Turn them every day or two for the first week so they don't flatten on one side.

Expect two to three weeks, and up to a month for the biggest ones. Keep them away from radiators, airing cupboards, ovens on a low setting and hairdryers. Fast heat splits the shell and shrinks the inside away from it, leaving something brittle and hollow that shatters on the first decent hit. Slow drying gives you a conker that is hard all the way through.

They will shrink, and the high shine will dull to a soft sheen. That is normal. A conker is ready when it feels firm everywhere, with no spongy spot near the cap scar.

If you find a hole

Keep suspect conkers out of the main box entirely. A round hole means a larva has left; a soft, sunken area or a dusting of frass means one may still be in there, and it will happily work through your best specimens. Bin it, or keep it somewhere separate if you are curious. No amount of sealing will fix a conker with something living inside it.

Sealing and finishing

Sealing slows moisture exchange and protects the surface, but it does not stop shrinkage or kill anything hiding inside. Do it after drying, never before. Test on a lesser conker first, and let finished pieces cure fully before stacking them.

• Nothing at all. Matte and natural, fine for a season of play. Expect further dulling and shrinking.
• Beeswax or furniture wax. A thin coat, buffed off, gives a warm sheen and a faint honey smell. Good for display pieces, though it won't waterproof them.
• Linseed oil. Darkens the shell to a deep mahogany. Apply in thin coats and allow days to cure; thick coats stay tacky and attract dust.
• Diluted PVA glue. Roughly one part glue to one part water. Cheap and quick, dries fairly clear, but can look chalky on darker conkers.
• Clear varnish or nail polish. The glossiest and toughest option, and the best choice for drilled, strung conkers. Two thin coats beat one thick one, with a few hours between.

Work in a ventilated space, and remember to seal the inside of any drilled hole, not just the outside. A cotton bud dipped in varnish does the job neatly.

Storing them so they survive to next autumn

Breathable beats airtight every time. A paper bag inside a shoe box is close to ideal. Cardboard boxes, cotton or hessian sacks and wooden trays all work. Airtight plastic tubs and polythene bags trap damp and turn conkers sweaty and mouldy within weeks.

1. Store in one layer, or two at most, with paper between the layers.
2. Add a silica gel sachet if the room is humid, and swap it out now and then.
3. Label the box with the year and what the conkers are for.
4. Choose a cool, dark, stable spot — a cupboard in a spare room, not a damp garage, a warm loft or a sunny windowsill.
5. Keep boxes off concrete floors and away from walls that draw damp.
6. Check once a month and remove anything soft, spotty or musty straight away, because mould spreads.
7. Move long-stored conkers into a fresh paper bag once or twice a year.

The fridge and freezer look tempting for long storage, but the damp and the thaw turn conkers to mush. A dry cupboard will always beat them.

Conkers for play: strings and hard shells

Drill after drying, not before. Use a fine bit at low speed, and support the conker — a cloth-lined vice, or your hand flat on a board — so it doesn't split along the seam. Thread strong string or thin cord through, knot it below, and you're ready.

A slowly dried conker is naturally hard, and a light seal helps it shrug off damp conditions. The folklore shortcut of baking them in a low oven does harden them fast, but it also leaves the shell brittle and prone to cracking. Patience over a few weeks is the better trade. And don't leave a strung conker sitting in vinegar — the string rots and the shell softens.

A word on safety: horse chestnuts are not edible. They are not the same as sweet chestnuts, and eating them can make people and animals ill. Keep them away from dogs and small children who might chew, and wash your hands after handling, especially before eating. If you think a child or pet has swallowed some, contact a doctor, vet or poison service for advice.

A simple routine that works

Gather and sort in October while the ground is dry. Clean and start drying the same week. Check for soft spots a fortnight in, and seal the ones destined for display once they are properly hard. Then box them up with a label and put them somewhere cool and dull, which is exactly where conkers are happiest.

Come next September, open the box, sort out the losses, and either use what's left or tip them onto the compost and start again. No gadgets, no special equipment — a couple of paper bags, a dry cupboard and a bit of patience will keep you in conkers for years.

Photo: RuslanSikunov / Pixabay