Last Updated on September 17, 2021 by Grow with Bovees
Every time I buy blue hydrangeas, they produce pink flowers the following year.
I hear people say that you can change the hydrangea color by altering the soil.
Is this really so?
Yes, fortunately, changing the color of hydrangeas is possible, and fairly straighforward, by adding things to the soil.
Unlike most plants, the color of the commonly grown hydrangea (Hydrangea macrophylla), as well as the intensity of the shade, is influenced by the pH level of the soil.
What Makes Hydrangeas Blue?
Hydrangeas planted in acid soils with a pH of approximately 4.5-5.5 will have flowers in shades of blue.
What Makes Hydrangeas Pink?
Hydrangeas planted in alkaline soils with a pH of 7.0 and higher, will mostly produce flowers in various shades of pink.
Is Changing the Hydrangea Color Easy To Do?
Yes, you can change the color of hydrangea flowers from blue to pink and vice versa.
Can I Change the Acid or Alkaline Levels of My Soil?
Unfortunately, it is difficult to change a very alkaline soil to an acid soil — and vice versa.
However, when your soil pH levels are more neutral, or only mildly acid or alkaline, then they can be altered, and the plants will produce the required blue or pink Hydrangea color.
Applying various types of chemical acidifiers — such as aluminum sulfate or Espoma GSUL6 (amazon link) — regularly to the soil will make it more acid, and the regular use of small quantities of agricultural lime will make it more alkaline.
These chemicals must be added regularly to the soil from about February onwards, since once the flower heads have formed, it is usually too late to influence the color of the hydrangea blooms. The soil pH is quite easy to check using an electronic soil tester.
Hydrangeas need a very rich growing medium and should therefore be planted into well-prepared beds with plenty of compost, old cow manure, and good garden soil.
You can use your hydrangea flowers for cut flower displays, which, with the correct cut hydrangea care, should last for a couple of weeks.
You will also find that the older varieties of hydrangeas — which, on the whole, have fairly small flower bracts — do not have such vibrant shades as the newer hybrids.
But, even so, if you want to have your hydrangeas producing flowers in both blue and pink shades — and your soil is relatively neutral — it is better to plant your hydrangeas in separate areas so that you can apply the right hydrangea fertilizers.
A great deal of work is being done on hybridizing hydrangeas and improving their colors. There are now certain red and white varieties that are completely colorfast and so will not be influenced by the soil conditions. If you are having problems with your hydrangeas not blooming, then check out our possible solutions.
Furthermore, many of the modern hydrangea hybrids do not seem to change as easily as the older types.
Therefore, if you want to have really good colors, it is advisable to buy named hybrids whenever possible.