Green Hydrangea Flowers

Hydrangeas, the blooming beauties of summer, show their summer blooms in pink, blue or white colour. But as the flowers age, we notice the colours changing into various shades from pink to green!

Causes Of Green Hydrangea
The question is what causes hydrangea blooms to change to green?

Changing Hydrangeas Colour With Age

Growing hydrangeas is very rewarding. They produce a remarkable display of colours over a long period of time, from Spring to Fall.

I had pink and blue colour hydrangeas displaying blooms since Spring, however I noticed that the original colours keep on changing. Now the blooms are of green colour! Why it is so? What encouraged the hydrangeas' blooms to change them to green colour?

There is one variety of hydrangeas, Annabelle hydrangeas, that  has initially white bloom but  ALWAYS turn green when they have been in bloom for about a few weeks.

But the blooms of other varieties that are normally pink or blue turn to different colours as they age.

Some hydrangeas begin in various shades of green, then turn a deep blue before finishing up in a maroon shade. Limelight hydrangeas naturally produce bright lime-green flowers. As they age, they  turn to pink and then to white to burgundy. (Green Colour Hydrangeas | How to change colour of Hydrangeas)

The most common colour for pink and blue hydrangeas to turn is green as they age, and then they may change to the shades of pink and burgundy. But often it occurs for only one or two years and then the blooms return to their normal colour for reasons as yet unknown. The greenish blooms is usually a temporary phenomenon.

To understand the cause of change of colour of hydrangeas, we should understand that actually the blooms as we see are not petals, but are actually colourful sepals that look like petals.

Sepals are those parts of the flower which enclose the petals and are usually green, and protects the flower bud. Hydrangeas have modified showy sepals called sterile flowers that are often referred to as petals. In one whorl hydrangea, the whorl is made up of sepals and the petals are missing.

The large flowers with huge round heads of mophead or hortensia hydrangeas are made up of numerous sterile flowers. Some hydrangeas like lacecap hydrangeas have a centre cluster of small fertile flowers, which are not showy, surrounded by a ring or two of attractive sterile flowers.

At the start of the bloom, the sepals are light green, but as they age, the pink, blue or white pigments overpower the green.  With age, the blossoms often end up in green.
The above picture shows colourful hydrangeas in late summer which were originally pink in Spring. This part of the plant was always positioned towards the brighter side, but not in sun.
Pink - Green Hydrangeas
Pink - Green Hydrangeas
The above picture shows two-colour  hydrangeas in late summer which was originally pink in Spring. The plant was not positioned in the sun but this side received non-even brightness, causing the bloom to change colour as shown.

Green Hydrangeas - original colour was pink
Green Hydrangeas
The above picture shows green hydrangea bloom in late summer which was originally pink in Spring. This portion was always positioned towards the darker side.

Research has shown that all coloured sepals contain the same anthocyanin, delphinidin 3-glucoside, so this is not responsible for developing the wide variety of colours.
  1. One reason for changing colour of hydrangeas is due to climate. Cooler temperatures encourage deeper coloured flowers. In the peak summer, the colours were pink or blue but as the end of summer,  the days  becoming shorter, the green colour started to appear.
  2. I noticed that those flowers which did not receive light remained green longer. It means, their colour change depends on the amount of light they receive. The green hydrangea flowers change in colour with longer days of light. Light gives those colours the energy to dominate. When the days are becoming shorter, the blue, pink and white pigments lose energy and once again turn to green. The colour can last for weeks and then you find your hydrangea flowers change again.
  3. The colour of the sepals is influenced by the availability of aluminium ions in the soil. Acidic soils help absorb the aluminium ions in the soil and make the flower heads blue. In alkaline soils due to the absence of aluminium ions, the flower heads tend to be pink. White hydrangeas do not have pigment in their sepals and are white regardless of the soil pH.
If you really want to enjoy your showy hydrangeas, then why to bother; don't reason out the Mother Nature, simply enjoy!

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1. Yoshida K, Ito D, Shinkai Y, Kondo T.,  Change of color and components in sepals of chameleon hydrangea during maturation and senescence, http://www.ncbi.nlm.nih.gov/pubmed/18423783