To make blackberry simple syrup, combine 1 cup fresh or frozen blackberries, water and sugar in a medium-sized saucepan over medium-high heat until mixture comes to a boil and sugar has dissolved completely. Remove from heat then set aside to cool.

Once mixture has cooled, strain through a sieve, discarding the pulp and seeds. This should yield about 1½ cups of blackberry syrup.

To make lemonade, combine lemonade, ½ cup syrup and lemon juice in a large pitcher. Stir well to ensure ingredients have combined completely. Serve in glasses filled with fresh ice.