You can change the color of your hydrangea blooms

Published 9:31 pm Friday, June 23, 2017

Often purchased as a gift plant, bigleaf hydrangea can be transplanted into the garden and enjoyed year after year. Bigleaf hydrangea prefers morning sun, afternoon shade and moist, well-drained soil.

Also called French, Japanese or snowball hydrangea, this plant is known for its flower colors that can be changed from pink to blue or from blue to pink by adjusting the soil pH. The color variation is due to the presence or absence of aluminum compounds in the flowers. If aluminum is present in the plant, the flower color will be blue. If it is present in small quantities, the color will be in between, or violet. If aluminum is absent, the flowers will be pink.

Soil pH indirectly affects flower color by affecting the availability of aluminum in the soil. When soil is acidic, pH 5.5 or lower, aluminum is generally more available to the roots. When the soil is neutral or alkaline, pH 7.0 or higher, aluminum levels are decreased.

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To gradually change flower color from pink to blue, broadcast one-half cup of wettable sulfur per 10 square feet and water it into the soil. To make flowers pink, broadcast 1 cup of dolomitic lime per 10 square feet and water it into the soil. Granular products can be applied anytime throughout the year. However, it takes patience to change hydrangea flower colors.

A quicker way to change flower color is through liquid soil drenches applied in March, April and May. To make flowers turn blue, dissolve 1 tablespoon of aluminum sulfate in 1 gallon of water. To make the flowers turn pink, dissolve 1 tablespoon of hydrated lime in 1 gallon of water. Drench the soil around the plant with the solution. Avoid getting any solution on the foliage.

It’s not hard to change hydrangea flower color; simply decide which method best suits you. You can have hydrangea flowers of your color choice. 

Rebecca Bates is an MSU Extension-Lincoln County agent, and can be reached at 601-835-3460 or by e-mail at