Unlike other flowering shrubs, hydrangeas have the unusual ability to change their flower color.
However, not all hydrangea varieties can change their flower color from pink to blue and vice versa.
Learn how to make your hydrangeas blue or pink below.
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What are Anthocyanins?
Anthocyanins are water-soluble pigments in the “flower heads” or bracts.
When they are sparse and scattered, they appear pink.
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When less aluminum is absorbed, the molecules in the flower move apart, causing it to turn pink.
The amount of aluminum available to plants is determined by the soil’s pH level.
Perform the test according to the directions to determine the pH of the soil.
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Drench the soil around the hydrangea with this solution, taking care not to spill any on the leaves.
Warning
Do not measure amendments to the soil based on guessing or estimating.
Adding too much or too little may harm your hydrangea and surrounding plants.
Leftover grounds will increase the acidity of your soil therefore turning the blooms blue.
Sprinkle them in late fall and work them into the soil.
Repeat the process whenever you fertilize.
Add them to your soil and mix in well.
As the eggshells slowly break down, they will reduce the acidity of your soil.
Aluminum will be harder to absorb and your blooms are likely to turn pink over time.
Maintaining the Soil pH
Have patience after amending your soil.
Continue to test the soil during this time and further amend if necessary.
Changing the pH is a gradual process that does not happen all at once.
This can make changing your hydrangea color feel like an uphill battle.
There are hydrangea cultivars such asStrawberry SundaeandStrawberry Vanillawhose flowers change as the season progresses.
This color change has nothing to do with soil acidity, it is a result of the plant breeding.
To tweak the color towards more pink or bluer, follow the directions for soil amendments above.
The best fertilizer for blue hydrangea cultivars is a fertilizer for acid-loving plants.
Apply it once in the spring before the growing season starts.
Change the Color of Your Hydrangea?The University of Iowa Libraries.
Growing Tips: Hydrangeas, Color, and Fertilizing.
University of Massachusetts Amherst.
University of Georgia Extension.
