Why Do Hydrangea Flowers Turn Green?

A blooming hydrangea with green petals.
What You'll Need
Pruning scissors
Acidic fertilizer

Hydrangea flowers produce spectacular and colorful blooms in hues of blue, pink, white, and many shades in-between. But what causes hydrangea flowers to turn green?

Some Varieties Naturally Produce Green Flowers

Among the various cultivars, some naturally produce green hydrangea flowers. These include the limelight hydrangea, with its bright lime green flowers. On the limelight, older flowers turn from green to pink and then to white and finally burgundy, while new floral growth comes in the same spectacular lime green. Limelight hydrangeas grow from six to eight feet tall and wide.

Another variety is the Annabelle. In fact, the Annabelle hydrangea, which initially blooms white, will always turn to green flowers after it has been in bloom for a period of about two weeks. Sometimes, the blooms stay white a bit longer.

Changing Colors with Age

The prevailing opinion among hydrangea aficionados is that all hydrangea flowers just change color with age. Pink and blue hydrangeas most commonly turn green. In the south, where the climate is hot and sunny, these green-hued hydrangeas may begin to pick up shades of burgundy and pink. Some hydrangeas begin in various shades of green and then turn a deep blue before finishing up in a maroon shade.

Pink and blue hydrangeas may produce green flowers during some years for reasons yet unknown. The consensus is that this condition lasts only for one to two years before the plant returns to its normal coloring. Home gardeners can facilitate this return-to-normal flowering by adding an acidic fertilizer.

Climate Issues Affect Color of Hydrangea Flowers

Hydrangeas like morning sun and afternoon shade and don’t do well in drying wind. They also like relatively consistent temperatures—not too hot and not too cool. But as the blooms begin to grow, cooler temperatures encourage deeper colored flowers.

When a sudden cold snap, frost, snow, or freezing rain negatively affects a blooming hydrangea, all you can do is to cut back the flowers affected by the change in climate. The following year, or the next growing season, the hydrangea should flower as usual.

Some varieties of commercial hydrangeas, including lace cap hydrangeas, like cool conditions and a moist soil. For hotter climates, container-grown plants are best grown indoors and moved outside when weather turns cooler (but only on frost-free days). These can also have unusual changes if they are grown outside during hot seasons instead of inside.

Where soil does freeze, mulch should be applied right after. Any mulch material can be used to protect the hydrangea, including dried grass clippings, straw, evergreen boughs, or tree leaves.

Green-Flowering Is Generally Temporary

Unless the cultivar is specifically known to produce green flowers, the hydrangea that delights the eye with greenish blooms is usually a temporary phenomenon. Soon, it will either turn another color or end the color cycle with green hues.

In any event, many gardening experts consider the green-hued hydrangea flowers as yet another example of Mother Nature’s quixotic sense of humor and exquisite taste.