Rinse the lilacs: Gently rinse lilac blossoms to remove any dirt or bugs.
Infuse the water: Add petals to 3 cups cold water and let steep in the fridge for 4–6 hours or overnight.
Strain and mix: Strain out the petals, then stir in 1 cup lemonade concentrate. Add honey or sugar to taste.
Chill and serve: Pour over ice and garnish with lemon slices or fresh lilac blossoms.
No concentrate? Use ½ cup fresh lemon juice + ½ cup sugar or honey in place of concentrate.