Hydrangea flowers turn green is because their color naturally fades from bright colors to light green as they age through the year. Fewer hours of daylight means there is less energy for the hydrangea to produce the pigment responsible for colorful blooms and the flowers turn green.
Keep reading to learn why hydrangea flowers turn green and whether you can prevent the flowers turning green…
Why Hydrangeas Flowers Turn Green
| Reason: | Hydrangea Turning Green: |
| Life Cycle of Hydrangea Flowers: | Many different varieties of hydrangeas have flowers that turn green through the season due to age and as a response to seasonal change before the blooms turn brown. |
| Response to less hours of day light: | With less hours of day light the hydrangea has less energy and the pigments in the flowers that are responsible for the hydrangeas bright colors start to fade which turns the flowers green. |
| Heat and Humidity: | In higher temperatures and with greater humidity, hydrangea flowers appear more likely to turn green. This is thought that heat or drought stress could be contributing factors as could high humidity which is at odds with their natural environment. |
Life Cycle of the Flower- Hydrangea Flowers Turn Green as they Age
The most common reason for hydrangea flowers to turn green is because it is a part of the life cycle of the flower. Hydrangea flowers change color over the course of the season as they react to the changing seasons and begin to age. They often start with their original color, then turn green and eventually brown at the end of the season.
This is a common cycle of hydrangea flowers and the fact that your flowers have turned green may not indicate any problems or environmental stress but because the concentration of color pigments in the leaves changes over the course of the Summer with the flowers ending up green.
Green flowers are not to the determinant of the hydrangea.
Hydrangeas are not like other plants in that the color of the blooms changes over the course of the season and the flowers do not stay one uniform color.
The rate at which hydrangea flowers turn green varies each year and can depend on the varties of hydrangeas as some hydrangeas varieties turn green more readily then others.
If the flower has turned green then the change in color is not related to the acidity and alkalinity of the soil or the presence of aluminium sulfate which can causes color changes.
However it should be noted that a change in soil acidity can cause some hydrangea varieties to change the color of their blooms from blue (indicating acidic soil) to pink (indicating alkaline soil) if changes to the soil pH occur.
Day Length Contributes to Hydrangea Flowers Turning Green
Hydrangea flowers turn can green in response to less hours of daylight. With fewer hours of sunlight there is less energy for the flower heads to produce the blue, pink or white pigmentation in the blooms. This causes the hydrangea flowers to fade from their original color to green in late Summer.
It is thought that it is not necessarily the intensity of the light that turns the flowers green but the shorter day lengths.
This is why at the end of Summer with less hours of light, is when the hydrangea flowers most often turn green whereas at the height or Spring with more hours of daylight the plant has the energy to produce the more colorful pigments in the flowers.
However I must emphasize it is important not to interpret this as advice to place your hydrangea in more intense sun.
Hydrangeas are woodland plants that grow naturally under a tree canopy and most varieties do not tolerate full sun as it can scorch the leaves and flowers brown so always plant your hydrangeas in dappled light or morning sun followed by afternoon shade.
Heat and Humidity- Green Hydrangea Flowers
It is thought that heat and humidity could also contribute to hydrangea flowers turning green. Hydrangeas turning green appears to be a more prevalent problem in climates that are hot and high in humidity, but the exact reason for this is somewhat mysterious.
Hydrangeas are thirsty plants that require the soil to be consistently moist to prevent the leaves and flowers wilting.
If the temperatures are high then the hydrangea can be under stress as the root system cannot draw up moisture quickly enough to replace the moisture loss from the leaves.
It is thought that this type of stress combined with the humidity can hasten the hydrangea flowers turning from their original color to a pale green or even brown.
Hydrangeas can tolerate some heat and humidity but it is slightly at odds with its natural woodland environment where hydrangea originate, so this may be a reflection of conditions that are different to which they are adapted.
(Read my article, how to revive a dying hydrangea).
How to Stop Hydrangeas Turning Green
To prevent hydrangea flowers from turning green it is important to replicate the conditions of their native environment with dappled sunlight, watering often to keep the soil moist and to use a well balanced fertilizer in the Spring to ensure the hydrangea has all the nutrients it requires.
Even with the best care practices, hydrangeas flowers can still turn green at the end of the season as they age or in reaction to less hours of light resulting in a lower concentration of the color pigments in the flowers.
Often the exact cause of hydrangeas turning green is unknown, but fortunately hydrangeas can thrive even if their flowers turn green.
Hydrangeas can sometimes even turn green for a year or two then revert back to their original color for reasons that are not clear.
(Read my article, why is my hydrangea turning brown?)
Some Hydrangea Varieties Naturally Have Green Flowers
There are of course hydrangeas such as Hydrangea paniculata ‘Limelight’which have naturally occurring green flowers which look very elegant. This particular variety stays a lime green throughout the season, therefore the color green is within the range of colors that hydrangea display their flowers.
(Read my article, why is my hydrangea not blooming?)
Key Takeaways:
- The reason hydrangea flowers turn green is because the color fades at the end of the growing season. With fewer hours of daylight the hydrangea has less energy to produce the pigments that are responsible for blue, white and pink flowers, so they blooms turn green.
- Heat and humidity is at odds with the hydrangeas natural environment and is thought could contribute to the flowers turning green.
- Some hydrangeas have naturally green flowers such as Hydrangea paniculata ‘Limelight’ which stay green throughout the year.
- Hydrangea flower turning green is common and does not mean there is a problem with the hydrangea. Usually the flowers fade and turn green at the end of the blooming period before the flowers turn to a brown color