Can white hydrangeas turn blue or pink?
Written by
Nguyen Minh
Reviewed by
Prof. Martin Thorne, Ph.D.White hydrangeas don't change colors based on soil, because they are naturally white. Genetically, they are not equipped with color-changing pigments! Unlike bigleaf varieties, they can't produce the anthocyanins responsible for the pH- and aluminum-dependent blue blooms. Adding a little aluminum sulfate and lime only risks burning the roots and does nothing for your blooms. I learned that lesson well, especially after spending an entire season trying to turn my 'Annabelle' hydrangeas blue!
Genetic Pigment Absence
- Lack delphinidin anthocyanins that react to aluminum
- Produce only white flavonol pigments
- Color genes absent in DNA structure
Soil Treatment Ineffectiveness
- Aluminum sulfate cannot create blue without pigments
- Lime fails to produce pink without responsive chemistry
- Amendments accumulate causing nutrient lockout
Risks of Forced Changes
- Root burn from excessive aluminum sulfate
- Alkaline toxicity from lime overdose
- Reduced bloom production from stress
For the science part, it's all about the pigment genetics. Our white hydrangeas are producing kaempferol glycosides instead of anthocyanins. These particular pigments do not combine with aluminum ions. Even in perfectly acidic soil, the blooms remain pure white. My botany professor at university backed me up when I did this research.
That struggle for blue kills white hydrangeas. Aluminum sulfate will burn the roots at the required levels for blue, while lime makes the medium too alkaline, producing an iron deficiency. One of my clients killed her hydrangea because she kept adding various substances to the soil, altering its composition. Healthy white hydrangeas require a neutral pH 6.0-7.0) to develop strong, healthy blooms.
Longing for a little color-changing magic in your garden? Choose the right varieties. Bigleaf (or mophead) hydrangeas, such as 'Endless Summer', change from lovely pink to blue, or vice versa, depending on the soil chemistry. Mountain hydrangeas. They're purple!!) Choose to plant those instead of trying to force white varieties into a pretty color. Now, I have both white varieties and color changers!
Appreciated for their unique beauty, the white hydrangeas will brighten a shady corner far better than the coloured variety, whose flowers are, as a rule, less permanent in the cut state, and I use my own to form a background to gay annuals, thus recognising their true, though rather unnatural position in the border.
Read the full article: Soil pH for Hydrangeas: Color Control Guide
