Sloes are a European plum sometimes found in the wild as escapees from cultivation. They are the blue-black, tart fruit of the Blackthorn tree (Prunus spinosa).
Most wild sloe trees grow from 5 to 15 feet high and are not particularly attractive. They have twisted, omni-directional branches, often with significant thorns. They are often found in thick stands of intertwined, thorny branches. The fruit, when ripe, is typically globular and small, from 3/4 to 1 1/2 inches in diameter.
Wild sloes make an excellent wine but, like cherry wine, must be aged for some time to "come into its own." When fermentation ends, wild sloe wine is not pleasant and the winemaker will be tempted to either over-sweeten it to overcome its astringency or toss it out altogether. Either course of action would be a mistake. Simply put the wine in a dark, cool place and forget about it for at least one year. Sloe wine is best when finished slightly sweet, but it does okay as a sweet or dessert wine and is very good with glazed or stuffed fowl, especially wild fowl.
Put 1/2 gallon water on to boil. Meanwhile, wash, sort, destem, and destone the fruit. Transfer fruit and any juice to nylon straining bag in primary graduated (marked) by pints to one gallon, add grape concentrate, boiling water, cover and allow to cool to lukewarm. Add crushed Campden, recover and wait 12 hours. Crush fruit by hand by squeezing bag. Mix in half the sugar, stirring well to dissolve. Lift the bag of fruit and allow to drain about two minutes, then add water to bring liquid up to 7 pints. Return bag to liquid, measure and note S.G., and then add acid blend, tannin, pectic enzyme, and yeast nutrient. After 12 hours, add yeast. Twice daily squeeze bag of pulp. After 7 days of fermentation, drip drain bag of pulp 2-3 hours, squeezing gently at end to coax additional juice from bag. Add drained juice to primary and use hydrometer chart to determine how much additional sugar to add to achieve S.G. of 1.095 (find previously measured S.G. on chart and determine how much sugar to add to that to achieve target S.G. of 1.095). Add sugar and stir well to dissolve. Allow to settle overnight and then rack into secondary and fit airlock without topping up. After 7 days top up. Rack after one month, top up and refit airlock, and repeat after additional two months. When wine clears, wait one additional month, rack, top up, refit airlock, and set aside for bulk aging. Check water level in airlock monthly. After 6 months stabilize, wait 10 days, rack if needed, sweeten to taste and bottle. Do not drink for one year.[Adapted recipe from W.H.T. Tayleur's The Penguin Book of Home Brewing & Wine-Making]