Which hydrangeas can change color?
Written by
Michael Sullivan
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Only select varieties of hydrangeas have the special characteristic of altering bloom colors as a result of soil chemistry. This color change is uniquely possible through plants that actually have a structure of pigment that is responsive to aluminum ions. Any effort you undertake to change bloom color should only focus on the right responsive varieties, so you are not disappointed.
Color-Changing Varieties
- Bigleaf hydrangeas (Hydrangea macrophylla): Classic mophead and lacecap types
- Mountain hydrangeas (Hydrangea serrata): Smaller blooms with intense color shifts
- Genetic factors: Cultivars like 'Nikko Blue' have stronger color potential
Fixed-Color Varieties
- Smooth hydrangeas (Hydrangea arborescens): 'Annabelle' stays white regardless of soil
- Panicle hydrangeas (Hydrangea paniculata): Blooms transition white-pink but not blue
- Oakleaf hydrangeas (Hydrangea quercifolia): White flowers unaffected by pH changes
Specific anthocyanin pigments, which form complexes with aluminum, are the basis for the color change mechanism. Both bigleaf and mountain hydrangeas produce anthocyanin pigments. Other varieties of hydrangeas produce no anthocyanins at all. I have tested more than twenty cultivars, with both bigleaf and mountain hydrangea species transforming with soil amendments. White varieties, such as 'Annabelle', are suitable for any soil condition.
Genetics influence the potential for depth of color variation within the changing varieties. Some varieties, such as 'Nikko Blue', are genetically predisposed to blue, and others, such as 'Pia', are genetically unresponsive to lightening. If you are considering plants, then look at nursery labels for notes on color flexibility. I always choose a plant listed on the label as color-responsive.
Soil chemistry functions only on anthocyanin-rich sepals of bigleaf and mountain hydrangeas. Their flower pigments all contain delphinidin that can bind with aluminum ions. Other types of hydrangea have pigments that do not react to changes in pH. The botanical information explains the limited range of color transformation.
Verify the kind of hydrangeas you are dealing with before attempting any color alterations. The shape of the leaves can help determine the type: bigleaf varieties have rounded leaves while oakleaf hydrangeas have lobed leaves. Mountain hydrangeas have small leaves with serrated edges. Knowing the difference will prevent you from trying to change the color of a plant that simply won't change color by a basic pH change.
Read the full article: Hydrangea Color Change: Ultimate Guide
