Turning Hydrangeas Blue or Pink
Blue, pink or white hydrangea flower color depends on the type and soil pH.
White hydrangeas are always white no matter your soil pH. New introductions of pink and ruby colored Annabelle type hydrangeas have increased our options.
Panicle hydrangea flowers start out white or lime green, then fade to pink or red. Changing the soil pH or adding aluminum to the soil will not make these blue.
The popular pink and blue flowering big leaf hydrangeas produce pink flowers in high pH soils where aluminum is bound to the soil and unavailable to the plants. You’ll have blue flowers in acidic soil where the aluminum can be absorbed by the plants.
Adding aluminum sulfate can help those gardening in high pH soil grow blue flowers. Repeated use over time can result in aluminum toxicity.
A bit more information: Consider using elemental sulfur when trying to grow blue hydrangea blooms in high pH (alkaline soils). This reduces soil pH over time, making the aluminum available to the plant. It is a slower process but eliminates the risk of aluminum toxicity from overuse of aluminum sulfate. Those struggling to grow pink hydrangea flowers in acidic soil can raise the pH with lime. Always have a soil test before adding lime or sulfur to the soil. Misapplications can cause other issues for many years. The easiest option is to embrace the color nature provides. You may find it less frustrating.
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