Sloe gin is arithmetic. It wants about three months in the jar, and there is one short window in the year when the hedgerows are loaded and the calendar still leaves room. That window is now.

The work takes twenty minutes. Everything after that is waiting, which is the easy part and the part you cannot compress.

Finding sloes

Sloes are the fruit of the blackthorn, a dense, thorny hedgerow shrub found along field edges, lanes and scrubland across most of Britain. The fruit are small, round and blue-black with a dusty bloom, like a plum shrunk to the size of a marble, and they cluster tight against the branch.

They are also brutally astringent raw. If you try one and your mouth dries to the back of the throat, that is a sloe, and that is what the sugar and the three months are for.

Before you pick, the usual rules. The Woodland Trust’s foraging guidelines note that removing wild plants without the landowner’s permission is illegal, and ask foragers to take no more than they plan to use. A hedgerow that looks limitless is feeding birds through the winter. Take a bagful, not a bucketful.

The frost question, settled

Every sloe gin conversation stalls here. The tradition says wait for the first frost before picking.

The Woodland Trust is relaxed about it: it is “traditional to pick sloe berries for gin after the first frost, but there’s no reason why you can’t pick them earlier, bag them up and pop them in your freezer”. The reasoning is mechanical rather than magical. As the Trust puts it, “the theory is that the frost splits the skins so the juices can flow into your gin without you having to go to the effort of pricking all the berries”.

So the frost is not doing anything mystical to the flavour. It is splitting skins. A night in the freezer splits them just as well, and it means you can pick today and start tomorrow rather than waiting on the weather.

This matters more than it sounds. Wait for a real frost in much of southern Britain and you may be waiting until November, by which point Christmas is a stretch.

The ratio

The classic proportions are roughly equal weights of sloes and sugar to a standard bottle of gin. Our homemade sloe gin recipe works to 450g of each against a 70cl bottle, and says to keep it at least three months before serving.

That ratio is a starting point, not a law. Less sugar gives something drier and more astringent, closer to a bitter aperitif. More gives a rounder, sweeter liqueur. You can also hold back a third of the sugar, taste at eight weeks and add the rest then, which is the safer route if you are unsure.

On the gin itself: use a mid-range London dry. The sloes and sugar will paper over most of what makes an expensive bottle worth its price, so there is genuinely nothing to gain from a premium gin here.

The method, briefly

Freeze the sloes overnight. Sterilise a large jar. Tip in the frozen sloes and the sugar, pour over the gin, seal.

Turn the jar end over end every day for the first week or so, until the sugar has dissolved and the liquid has gone a deep ruby. After that, put it somewhere dark and forget about it. Strain through muslin before bottling.

That is the whole process. The only way to get it wrong is to drink it too early.

Three more worth starting now

The same method works across the hedgerow, and all three are at their moment.

Damson gin. Damsons are ripe now and make a rounder, jammier, less austere drink than sloes. Use slightly less sugar, since the fruit brings its own.

Blackberry whisky. Late blackberries, which are past their best for eating, are ideal for this. Whisky handles the fruit better than gin does.

Hedgerow gin. Whatever you have: sloes, damsons, a few blackberries, a couple of crab apples. Less predictable, often better.

What to do with the leftovers

Do not bin the strained sloes. They are boozy, sweet and still full of flavour, and they go into a fruit cake, a steamed pudding, or stirred through mincemeat.

Which is the other argument for starting this week. Strain in December and the fruit lands exactly when the baking starts, ready to go into clementine and sloe gin mince pies alongside the drink itself.

Pick this week. Freeze tonight. Open it at Christmas.

Sloe gin: your questions answered

When should you pick sloes?

The Woodland Trust says it is “traditional to pick sloe berries for gin after the first frost, but there’s no reason why you can’t pick them earlier, bag them up and pop them in your freezer”.

Do you have to prick sloes?

Not if you freeze them. As the Woodland Trust explains, “the theory is that the frost splits the skins so the juices can flow into your gin without you having to go to the effort of pricking all the berries”. A night in the freezer does the same job.

How long does sloe gin take?

Give it at least three months. Our own homemade sloe gin recipe says to keep it for at least that long before serving, which is why late September is the moment to start if you want it for Christmas.

What gin should you use?

A mid-range London dry. The sloes and sugar will cover most of what makes an expensive gin worth the money, so there is nothing to gain from a premium bottle.