Sloe gin is made from ripe sloes, which are traditionally picked after the first frost of winter (late October to early November in the northern hemisphere). Each sloe is pricked, traditionally with a thorn taken from the blackthorn bush on which they grow. An alternative folktale says that one should not prick the sloes with a metal fork unless it is made of silver. A modern variation is to pick the sloes earlier and freeze them.

A wide-necked jar is filled half way with pricked sloes and 4 ounces (110 g) of sugar is added for each 1 imperial pint (570 ml) of sloes. The jar is then filled with gin, sealed, turned several times to mix and stored in a cool, dark place. It is turned every day for the first two weeks, then each week, until at least three months have passed.

The gin will now have a deep ruby red colour. The liqueur is poured off and the sloes discarded, or infused in white wine or cider, made into jam, or used as a basis for a chutney or a filling for liqueur chocolates. The liqueur can be filtered, but it is best decanted back into clean containers and left to stand for another week. Careful decanting can then ensure that almost all sediment is eliminated, leaving a red liqueur that is not cloudy.

Recipes for sloe gin vary depending on the maker’s taste. The sweetness can be adjusted to taste at the end of the process, although sufficient sugar is required while the drupes steep to ensure full extraction of flavour. When made sufficiently slowly, the alcohol extracts an almond-like essence from the sloes’ stones, giving sloe gin a particular aromatic flavour. However, some recipes use a shorter steeping time and include a small amount of almond essence. Another common variation is the addition of a few cloves and a small stick of cinnamon.