Our tips for collecting elderflowers are to make sure you have identified the right plant, wait for a sunny morning and gather the blossoms without too much green stalk, taking care not to over crop one spot.
For four litres of cordial you will need around 1.5. litres of water; 20 rinsed flower heads (which have masses of tiny individual flowers); two and a half kilograms of sugar, two lemons; 85 grams of citric acid (available from a chemist) and clean, glass bottles. In a large saucepan, gently heat the sugar in the water till dissolved, stirring occasionally. Take the zest from the lemons with a potato peeler and then slice them. Bring the pan of syrup to the boil, then remove from the heat. Add the flowers, lemons, zest and citric acid. Stir well. Cover the pan and leave to infuse for 24 hrs. Line a colander with a clean tea towel and sit it over a large bowl. Ladle in the syrup and let it drip slowly through the towel. Pour into the bottles and keep in the fridge.