Gather Lilacs. Carefully pull individual blooms off of the flowers.
Measure out 2 cups freshly picked flowers.
Put blooms in a fine mesh strainer and rinse off.
Place rinsed Lilacs in a bowl. Set aside.
In a medium saucepan, bring the Water and Sugar to a boil.
Remove from heat and add the cut Blueberries. Let cool down to room temperature, lukewarm.
Once the Sugar/Water/Blueberry mixture is cooled, pour over the Lilacs.
Add the Lemon Juice. Stir to mix thoroughly. Cover and let steep for 12-24 hours.
After steeping, pour through a fine mesh strainer, pressing the petals to squish out all of the Lilac Syrup.
Transfer to an airtight container. It will keep in the refrigerator for up to 2 weeks. For longer storage, you can put in canning jars and water-bath can them. I have also frozen the syrup, which actually turns it into a "slush". You can use the slush just as you would the liquid syrup, adding it to drinks.