How to Change the Color of a Hydrangea Blossom From Green to Blue
Not all hydrangeas change color. Naturally white hydrangeas will say white no matter what. However, plants such as the variety known as Big Leaf Hydrangea will turn blue in soil with an acidic pH lower than 6.0, and red or pink in soil with an alkaline content. The color change is due to the amount of aluminum in the soil. There is more aluminum present in acidic soil than in alkaline soil. To change the color of your hydrangeas, change the pH of the soil. Does this Spark an idea?
Other People Are Reading
Instructions
-
-
1
Determine the pH of your soil by taking a sample of soil from the drip line of your hydrangea bush. Most pH testing kits come with a liquid that will change color when added to a solution of soil and water. The color that the solution turns helps to determine what your soil pH is.
-
2
Scratch a cupful of lime into the dripline of your soil beneath the hydrangeas to increase the pH of soil, or turn it more alkaline. Use aluminum sulfate to lower the pH, or make it more acidic.
-
-
3
Water the soil well with a watering hose to soak the soil amendments into the soil.
-
1
Tips & Warnings
Because you can more completely control the elements in the soil of a potted hydrangea, it is easier to change the color of potted varieties than it is to change the color of hydrangeas that have been planted in the ground. For example, a hydrangea planted near a sidewalk or foundation may be more alkaline due to the lime that leaches from the cement into the soil.
It is easier to make a pink hydrangea blue than it is to turn a blue hydrangea pink, because changing the color of a pink hydrangea entails adding aluminum to the soil, while changing a blue hydrangea means blocking it from taking up the aluminum that is already present in the soil.
Be careful not to use too much lime or aluminum. Doing so can change the soil's pH too quickly and burn the roots.
You should wait until a plant is at least two years old and well-established before attempting to change the color of the plant.
It is impossible to change the intensity of a hydrangea's hue, because it is affected by factors such as plant genetics and weather. For example, a vivid red hydrangea is impossible to achieve in the south, where the climate is humid and summer temperatures are very warm.
