Most commercial sloe gins today are made by flavoring the less expensive neutral grain spirits and produce a fruit cordial effect. The most popular commercial brands of sloe gin are Plymouth and Gordon's. Hawkers also produce a Sloe Gin, the only manufacturer to do so with a Royal Warrant.
To make sloe gin, the sloe berries must be ripe. They were traditionally picked in late October or early November after the first frost of winter, although with spring now arriving earlier followed by warmer summers, the berries are now ripe by mid-September. A wide-necked jar that can be sealed is needed. Each berry is pricked, and the wide necked jar is filled half way with the pricked berries. Folklore has it that when making sloe gin, you shouldn't prick the berries with a metal fork, unless it is made of silver. The established traditional method is to prick the berries with a thorn taken from the blackthorn bush on which they grow.
For each pint (0.5 litre) of sloes, 4oz (100g) of sugar is used, then the jar is filled with gin, adding a few cloves and a small stick of cinnamon, as well as the almond essence. The jar is sealed and turned several times to mix, then 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 be a deep ruby red. The liqueur is poured off and the berries and spices discarded. Alternatively, the left-over berries can be infused in cider, made into jam, used as a basis for a chutney or made into 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 clear liqueur.
Made in this way, the alcohol extracts an almond-like essence from the sloes, avoiding the need to add almond essence. Home made sloe gin is a much more complex and subtle drink than that produced commercially. The sweetness can be adjusted to taste at the end, but sufficient sugar is required at the start of the process to ensure full extraction of flavour from the sloes.
In a diary entry dated 22 August 1938, George Orwell pasted a newspaper clipping of a recipe for sloe-gin purportedly from "New Forest gypsies."