Shake out the elderflower umbels well and wash briefly.
Mix the water with the sugar, citric acid, the sliced lemons and the preserving aid, insert the cones and stir. Let stand in a cool place for 4-5 days, stirring occasionally until the sugar has completely dissolved.
Then filter through a cloth and fill the syrup into bottles with screw caps.
The syrup tastes ice cold as a refreshment with water, sparkling wine or prosecco.