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Controlling Hydrangea Bloom Color in Marietta, GA

Posted by Christine Crandall on Mar 29, 2019 11:20:04 AM

Every Georgian is familiar with the giant, blue blooms of the hydrangea that bless everyone with their whimsical, snowball-like appearance each summer. They are beautiful, and the blooms last long into late summer/early fall months. But what about pink hydrangeas? Sometimes, hydrangeas exist in a multitude of colors from pink to blue. More importantly, you can control your hydrangea bloom color by controlling the pH of the soil.


You may be wondering why anyone would want to stray from the vibrant, pastel hue of classic blue hydrangeas. The answer is variety. In a world of blue hydrangeas, pink hydrangeas stand out as unique and beautiful. In other areas of the world, where pink hydrangeas dominate, blue is the preferred color.

The blue color comes from Georgia’s acidic soil, which contains aluminum ions that cause the Hydrangea bloom to change color. It isn’t actually the bloom. Like the dogwood tree, the part of hydrangeas recognized as its blooms are actually modified leaves. These color-changing leaves are called sepals, and they respond to changes in pH. Pink hydrangeas respond to alkaline soil, or soil with a higher pH.

Changing your soil pH for one plant can be accomplished during the watering process. To change to pink hydrangeas, lime should be mixed with water and applied to the plant. If you are looking for blue hydrangeas, it should be sulfur…or maybe some aluminum sulfate.

Hydrangeas will not change color overnight. They may not even change in one growing season, but you should see some results within two growing seasons. The change from pink to blue gives your landscape an entirely new feel. It can be very refreshing to have such a color change without having to establish new plants.

Other ways to increase acidity for blue hydrangeas include the application of ground citrus peels, egg shells, or coffee grounds.

Hydrangeas are often taken for granted in Georgia landscapes because they are relatively easy to grow, and they have long-lasting blooms that make homeowners happy with their minimal effort. However, they can also be a fun project in the science of pH. Seeing your hydrangea color change over the years will be a rewarding show of your gardening efforts.

Pink or blue….or anywhere in between, hydrangeas are a common southern flower of which it is difficult to tire. The blooms, or sepals, are beautiful in any color. However, if you want a change, it is an option if you want to play around a little with soil acidity or alkalinity.


Have questions about your soil? 

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Topics: soil amendment