Nice, @iserbrown - interesting that you have both colours with your hydrangeas! Doesn't one need an acid soil for their colour & the other an alkaline soil? Well done on having both! Do you add anything to the soil to promote that happening?
Yep ... googled it ...
Generally speaking, acidic soil, with a pH lower than 6.0, yields blue or lavender-blue hydrangea blooms. Alkaline soil, with a pH above 7.0, promotes pinks and reds. With a pH between 6 and 7, the blooms turn purple or bluish-pink. To lower your pH, add garden sulfur or aluminum sulfate to your soil.