Hydrangea Turning Green? (3 Reasons)

Are your beautiful hydrangea flowers turning from pink, white, or blue to green, and you don’t know why?

When I worked as a gardener, I would see hydrangeas change colour to green usually at the end of the growing season and people would ask me why this happens.

So I did the research scouring hortiucltrual journals to find the reason, and I even had conversations with specialist growers but interestingly enough, I heard several possible explanations, however the truth is there is no scientific consensus on why hydrangea flowers turned green.

I found this fascinating! So, in this article, I discuss with you the possible reasons why the flowers turn green and what you can do about it!

Keep reading to learn why hydrangea flowers turn green and whether you can prevent the flowers from turning green…

Why Hydrangeas Flowers Turn Green

I made a table summarizing the main reasons I learned for hydrangeas turning green…

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 throughout 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.

I see this every year in the garden and to me, it signals a shift in the seasons.

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 throughout the Summer with the flowers ending up green.

Green flowers are not the determinant of your hydrangea.

I discovered that hydrangeas are not like other plants in that the color of the blooms changes throughout 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 varieties of hydrangeas, as I have personally seen some hydrangea varieties turn green more readily than others.

If the flower has turned green then I can tell you that the color change is not related to the acidity and alkalinity of the soil or the presence of aluminum sulfate which can cause 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 as the hydrangea cannot draw up aluminium sulfate in the same way.

I had one reader- Elizabeth- comment the following:

“Most of my hydrangeas are still blue and pink. However, a majority of them are green which is so unappealing to me. I really adore hydrangas and I feel like they are the most attractive blooming bush you can have framing a huge historical home.” -Elizabeth Williams

I, too, think it’s a shame that our beautiful hydrangeas lose the vibrant colour of their flowers. Do your hydrangeas have a mix of blue, pink AND green flowers? If so, please comment below, as I’m still actively trying to determine why this is and what commonalities I can spot in each case.

Day Length Contributes to Hydrangea Flowers Turning Green

Hydrangea flowers turn green in response to fewer 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.

From my research, it initially appeared that 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 fewer 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.

Having said all this, I have come across more hydrangeas that have had their flowers turn green, and I am working on a speculative theory that perhaps the intensity of light does have more of an impact on the reason hydrangea leaves turn green than I initially suspected.

The reason I say this is because I have seen a significant increase in the number of green flowers in years where we have had significantly more overcast days (with a lower light intensity) rather than a brighter sunny Summer. This, of course, could also be the case if a tree canopy in your garden has matured and is blocking out more light.

Have you noticed this too? Please leave a comment below this article, I’d really appreciate it!

Heat and Humidity- Green Hydrangea Flowers

This reason is one that I find most interesting!

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.

A grower who grows hydrangeas commercially taught me that this is more of a widespread anecdotal observation by growers and gardeners in different climates.

Hydrangeas are thirsty plants that require the soil to be consistently moist to prevent the leaves and flowers from 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, on how to revive a dying hydrangea).

How to Stop Hydrangeas Turning Green

To prevent your hydrangea flowers from turning green, what we need to do is replicate the conditions of their native environment with dappled sunlight, watering often to keep the soil moist, and 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 fewer hours of light resulting in a lower concentration of the color pigments in the flowers.

Often, the exact cause of hydrangeas turning green is often unknown, but fortunately, hydrangeas can thrive even if their flowers turn green.

I have even seen hydrangeas sometimes even turn green for a year or two and then revert to their original color for reasons that are not clear.

I can only speculate that this may be due to the nutrient availability in the soil. If you think this is why tour is turng green then I advise using a granular all purpose fertilizer, which can only help!

(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 I think 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.

Are your hydreangea turning green? If you have any other theories, then please comment below and share them with my gardening community!!

(Read my article, why is my hydrangea not blooming?)

Key Takeaways:

• Hydrangea flowers turn green 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 their blooms turn green.
• Heat and humidity are at odds with the hydrangea’s natural environment and are 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