About 25 elderflower heads
Finely grated zest of 3 unwaxed lemons and 1 orange, plus their juice (about 150ml in total)
Inspect the elderflower heads carefully and remove any insects (or just shake them, thats what I do). Place the flower heads in a large bowl together with the orange and lemon zest.
Bring 1.5 litres water to the boil and pour over the elderflowers and citrus zest. Cover and leave overnight to infuse.
Strain the liquid through a jelly bag or piece of muslin and pour into a saucepan. Add the sugar, the lemon and orange juice.
Heat gently to dissolve the sugar, then bring to a simmer and cook for a couple of minutes.
Use a funnel to pour the hot syrup into sterilised bottles. Seal the bottles with swing-top lids, sterilised screw-tops or corks. I usually bag some of it and freeze it too.