The species of elderflower in question is Sambucus nigra, a native hedgerow plant in Europe and the United Kingdom. A variety called ‘Black Lace’ has, as the name implies, gorgeous burgundy-black foliage. The pink sprays of flowers are mildly fragrant, and if you have two of them, the flowers will give way to burgundy fruit in late summer. I grow it alongside a regular green, white-flowered variety, often sold as “common elderberry,” on the theory that the fruit will be better if at least one of its parents is the old, wild strain rather than a newer specimen bred for good looks. Plant them in full or part sun (‘Black Lace’ develops more color in full sun; it goes a little green in shade), give them regular water, and if you want smaller, bushier plants, cut the taller branches down in mid-summer after they flower.
Cordials and sodas flavored with elderflowers are a very British thing, but it took an American distiller to recognize their potential. Rob Cooper, a third-generation distiller, tasted homemade elderflower syrup in a London bar and decided to create a liqueur from the flowers. The result is St-Germain, made in France’s Bordeaux region from fresh elderflowers that arrive at the distillery the day they are picked. The liqueur has a floral, fruity flavor somewhere between honey and pears; it has become internationally popular and makes a lovely addition to sparkling wine or just about any drink made with gin.
Elderflower cordial is made by dropping fresh, clean blossoms into simple syrup immediately after picking and washing them. (Simple syrup is equal parts sugar and water, brought to a boil and allowed to cool. Two or three cups would be about right.) Most people add sliced lemons and oranges, and if you want a little more preservative, try an ounce of citric acid, available at health food stores. A splash of vodka also serves as a perfectly respectable preservative. Cover and wait 24 hours, then strain into a clean jar. Store it in the fridge and use it up within a month.
The fruit, by the way, is a bit tart to eat raw, but people do make it into jams and wines. Just keep in mind that all elderflower fruit contains some amount of cyanide. S. nigra is lower in cyanide than our native American species, and ripe fruit across all Sambucus species is lower in cyanide than unripe fruit. Cooked fruit is safer than uncooked. So—be careful out there.