Turning Or Keeping Hydrangeas Blue

Hydrangea ‘Bailmer’

Turning or Keeping Hydrangeas Blue – Using Aluminum Sulfate 

The treasured deep blue color of Hydrangea blooms is dependent on both the variety and soil pH.

The deepest blues are achieved in soils with ample amounts of aluminum and are at their best when the pH is near or below 6.0. Blue colored varieties can change to pink if these soil requirements are not met. To attain the desired blue blossoms, apply Aluminum Sulfate multiple times throughout the fall and winter.  We recommend Master Nursery Hydra Blue. You can apply Hydra Blue in its granular form, or in drier winters, dissolve it in water to provide a drench. Multiple applications will give you the best color. The first application should be in November, followed by one in December and again in February. It is important to apply Hydra Blue when the Hydrangeas are without foliage, as it can burn the leaves.

Follow the directions for the application rates on the back of the Hydra Blue package

Tip:  An easy way to remember the application schedule is Thanksgiving, Christmas and Valentine’s Day. It is helpful to calendar it as well. 

Some of our favorite blue varieties include: ‘Nantucket Blue’, ‘Nikko Blue’, ‘Blue Enchantress’ and ‘Bailmer’.