Popsugar Living Spring Interesting Facts About Hydrangea 9 Facts Every Hydrangea-Lover Needs to Know June 19, 2018 by Maggie Winterfeldt View On One Page Photo 2 of 9 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 2 Their Color Is Determined by the Soil's pH You can control the color of a hydrangea's flowers yourself by adjusting the soil's acidity and alkalinity. Previous Next Start Slideshow SpringGardeningFlowers