With hydrangeas, you can create your color
While there are literally hundreds of hydrangeas to choose from, none keep us guessing more than the bigleaf hydrangeas, Hydrangea macrophylla. Sometimes they bloom, sometimes they don’t. Sometimes the flowers are blue, sometimes they are pink. How does this happen?
Bigleaf hydrangeas have the ability to change flower color, and while it may seem magical it is actually quite logical. Plant a bigleaf hydrangea and if your soil pH is 5.5 or lower (acidic) and your soil has an adequate amount of aluminum, then your flowers will be blue. If your soil pH is between 5.5 and 6.5, then your flowers can be purplish or a mix of blue and pink. If your soil pH is 6.5 or higher (alkaline), then your flowers will be pink.
You can alter the color of your bigleaf hydrangea flowers by altering the soil pH. Aluminum is also required for blue hydrangea flowers. Most soils have adequate aluminum but aluminum cannot be extracted from the soil if the pH is too high. Adding aluminum sulfate to the soil will help lower the soil pH and ensure aluminum is present. This enhances the blue color. For pink flowers, an alkaline soil is necessary and can be obtained by adding lime. How much aluminum sulfate or lime is needed to successfully change the flower color is dependent on your current soil pH and soil type. A soil test is available at your local Cooperative Extension Service to determine exact amounts needed.
The Original Endless Summer, Blushing Bride, Twist-n-Shout, and Bloomstruck hydrangeas are all in a series of reblooming hydrangeas. This means they have the ability to bloom on previous year’s stems and on the current season’s new growth. This ability ensures they can bloom repeatedly from early summer to fall. If you accidentally prune when you shouldn’t or we have a harsh winter and flower buds are killed on the previous year’s stems, they can still produce flowers on this year’s new growth. Select one or all four in this series for a low-maintenance beautiful hydrangea.
Shelly Nold from the 2016 April issue