Hydrangea Colors

Stupefying Things About the Changing Colors of Hydrangeas

The hydrangea genus contains many plants, bushes, and shrubs, that bear fruit and flower in a variety of colors. In this Gardenerdy article, we give you a few tips on changing the colors of hydrangea. Read on.
Gardenerdy Staff
Last Updated: Mar 9, 2018
A genus of about 70-75 plants, hydrangea contains flowering plants which have origin in countries from east and south Asia. Korea, Japan, and China are known to have the largest concentration of hydrangea species. Hydrangea plants are naturally found in three forms, i.e., shrubs, trees, and lianas; lianas are woody vines with long stems.

Hydrangeas have a special characteristic of changing color with aging. Flowers can be found in a variety of colors even if they are not altered (chemically). Natural colors include blue, purple, pink, reddish-wine, mauve, and many other shades. The Hydrangea macrophylla is a commonly grown species in gardens in the US. In terms of color change, the Hydrangea macrophylla produces desirable results quite frequently. This plant produces white, blue, and pink colored flowers in summer. A variety of Hydrangea macrophylla called Hydrangea macrophylla var. normalis produces pink flowers. Panicle Hydrangea (H. paniculata) produces blooms that are creamy white in color.

How to Change the Color of Hydrangeas

The process of changing colors is based on manipulating the light received by the plant and chemical composition of soil used for growing them. Change in soil pH brings about desirable changes in the color of hydrangeas. Checking/testing the pH of a given soil is the first step in the process of changing it and thereby, color of flowers.

Reducing the aluminum absorption by hydrangeas helps in changing their color to pink. Raising the pH of soil and maintaining it in the range of 6.0-6.5 is one way of reducing absorption. The pH of soil is raised by adding dolomite lime to the soil. Raising the soil pH any higher in order to make it alkaline, won't be of much help. Just maintaining the 6.0-6.5 range is recommended. Adding soil amendments like high phosphorus fertilizers to the soil also helps in reducing aluminum absorption by soil.

The procedure of turning hydrangea flowers blue in color, is opposite to that of the process mentioned above. In this case, the soil need to be made acidic and maintained in the range of 5.2-5.5. Presence of aluminum in soil is helpful in changing the color of flowers to blue. Aluminum is naturally present in almost all soils, and therefore, one can change the color to blue quite easily. Even if the soil is acidic and there is natural presence of aluminum, the addition of aluminum sulfate should prove to be useful. To maintain the blue color, one should add fertilizers that are low in phosphorus content and have higher percentage of potassium.

Limitations in Color Change

The limitations of color change in hydrangea are presented below.
  • It is not possible to change white flowers to pink/blue.
  • We know that changing the color of hydrangea flowers is possible; however, intensity of colors cannot be changed easily. There are many factors which play a role in the alteration of shades of hydrangea flowers. Some of these factors include temperature, humidity, and heredity of hydrangea varieties. At the most, one can attain a saturated color by fertilizing it once/twice every year.
  • Changing hydrangeas to a 'true red' color is not possible, no matter how much lime is added to the soil. It is possible to achieve only a deep pink and not red.
Hydrangeas are beautiful flowers with variety of colors. Methods/techniques of how to change the color of hydrangeas presented in the article should prove to be helpful. This way, it is possible to have different hydrangea colors that change with season.
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