A garden or allotment vine rarely gives enough grapes at once to eat fresh before the first ones spoil, and outdoor-grown dessert grapes are usually smaller and more pippy than the ones from a shop. Drying them into raisins solves both problems at once: the sugars concentrate as the water leaves, the skins toughen enough to keep, and a scattered, awkward crop turns into something that stores through winter. It takes a low oven and most of a day, nearly all of it unattended.

Harvest Garden Grapes and Dry Them into Raisins

What you need

1 kg ripe grapes from a garden or allotment vine, tasting sweet all the way through
2 large baking trays
1 roll baking parchment
1 airtight storage jar or container

Step by step

Taste a few grapes from different parts of the vine. They're ready once they taste sweet right through, not just where the sun has reached them.
10 min
Snip whole bunches from the vine with secateurs, cutting the stalk rather than pulling the grapes loose.
15 min
Pick over the bunches and remove any grapes that are split, shrivelled, mouldy or still hard and sour, along with stray leaves and insects.
10 min
Wash the grapes in a bowl of cool water, then pat them dry with a clean towel.
10 min
Pull the grapes off their stalks. Halve any larger ones on a chopping board, or pierce whole small ones with the tip of a knife, so moisture can escape through the skin.
15 min
Spread the grapes cut-side up in a single layer on trays lined with baking parchment, leaving gaps so air reaches all sides.
10 min
Set the oven to its lowest setting, around 60-70C (gas mark quarter or lower), and prop the door open 3-4cm for airflow.
5 min
Dry for 8-12 hours, turning the grapes over halfway through and swapping tray positions if using more than one shelf.
600 min
Check for doneness: raisins should be wrinkled all over and chewy, with no soft, wet pulp inside when you cut one open. Keep drying in one-hour stretches if still damp.
30 min
Let the raisins cool completely on the tray before storing; packing them away warm traps condensation that encourages mould.
60 min

Afterwards

Store the cooled raisins in a clean, airtight jar out of direct light; they'll keep for several months in a cool cupboard. Check the jar after the first week — condensation on the inside of the lid means they weren't fully dry, so tip them back onto a tray for another hour in a low oven. After that, check every month or so and discard any that have turned sticky, sour-smelling or spotted with mould.

Questions

Can I dry grapes that have seeds in them?

Yes. Pierce them with a knife tip before drying so moisture can escape. The seeds just mean more to pick around later, not a safety issue.

Do I need a dehydrator?

No. A domestic oven on its lowest setting with the door ajar does the same job, just less evenly than a dehydrator's fan.

Why are my raisins still sticky and soft after 12 hours?

They likely need longer, or weren't spread in a single layer. Crowded or stacked grapes trap moisture between them and dry unevenly.

Can I use grapes that aren't fully ripe?

They'll dry, but underripe grapes are sharp, and raisins made from them stay sour rather than sweetening. It's worth waiting.