Hydrangea Flowers - Red, White, or Blue?
Rosie Lerner, Extension Consumer Horticulturist, Department
of Horticulture, Purdue University
Hydrangeas are popular but can be challenging for Indiana gardeners.
There are numerous species and cultivars that show amazingly
diverse flowering characteristics, especially color. Depending
on the species, cultivar and environmental conditions, the flowers
may be pink to red, blue to purple, cream to white, or some shade
Many gardeners are awestruck when they see a gorgeous blue-flowering
hydrangea. Such a specimen is no doubt one of the big-leaf hydrangeas,
known botanically as Hydrangea macrophylla, which has
flowers that will be blue in acid pH soil, and pink in alkaline
pH soil. Since this species typically flowers on old wood and
is usually killed to the ground in much of Indiana, this plant
often disappoints as it produces abundant new foliage but no
flowers. If it does manage to bloom, much of Indiana has alkaline
soil, so flowers are more likely to be pink unless the gardener
treats the soil to lower pH substantially. There are some promising
newer cultivars that bloom on both old and new wood, such as
The hardier species that flower mostly on new wood include H.
paniculata and H. arborescens, and have white
blooms. For more information on the different types of hydrangeas
in Indiana, see http://www.hort.purdue.edu/ext/hydrangea.html.