Start by removing the florets from the branches, making sure to remove all green parts. Place the florets in a strainer and rinse in cold water. Place the clean florets in a large bowl.
In a saucepan, combine the sugar and water and let the mixture come to a boil. Gently stir until all the sugar has melted.
Add some blueberries to the syrup if desired (for color only!), and a splash of lemon juice until you reach the desired color.
Let the mixture cool until lukewarm, then pour over the lilacs. Leave at room temperature for 2 hours, then cover the bowl and place in the fridge for another 12-18 hours.
Pour the syrup through a fine mesh sieve into a clean container with a tight-sealing lid. Gently press the lilacs with a spoon to release all liquid. Store the syrup in the refrigerator, it keeps for a few days. Freeze in freezer proof containers if you don’t plan on using it all up in a few days!.
