Color-Changing Hydrangeas

Do you have hydrangeas in your yard? If so, what color are they? Today we’re going to be learning about what affects the color of hydrangeas and how you can change the color of your hydrangeas!

While some hydrangea plants are named by color (ex. Nikko Blue and Forever Pink), these names have very little correlation to what the color of the hydrangeas is going to be. The flower color is mostly dependent on the concentration of aluminum ions (Al+++) in the soil in which the hydrangea is planted. When the soil is acidic, aluminum is more available to the plant. When the soil is alkaline, aluminum is less available to the plant.

Blue hydrangea flowers are most prevalent in acidic soils with pH’s around 5.2-5.5. Before you plant your hydrangeas, check the pH of your soil using one of these experiments. If your soil’s pH naturally falls in the 5.2-5.5 range, then you can go ahead and plant your hydrangeas. If your soil has a higher pH, it may be tricky to get blue hydrangea flowers. The best option would be to plant your hydrangeas in an area that has a more acidic soil. You can also try to add soil acidifier, ammonium sulfate, or aluminum sulfate to get blue blooms, but alkaline soil tends to “lock up” the aluminum, making it difficult for the hydrangea plant to access.

Pink hydrangea flowers flourish in soils with pH’s of around 6.0-6.2. When planting your hydrangeas, first test the pH of the soil. If your soil’s pH is in the 6.0-6.2 range, then you can go ahead and plant your hydrangeas. If your soil has a lower pH, you can apply a high-phosphorus fertilizer to discourage the uptake of aluminum or raise the pH of the soil by applying Garden Lime. Enjoy your pretty, pink hydrangeas!

LaLiberte, Kathy. “Growing Blue Hydrangeas – Hydrangea Colors: Gardener’s Supply.” Gardener’s Supply Company, Gardener’s Supply Company, 4 Mar. 2019, www.gardeners.com/how-to/growing-blue-hydrangeas/8609.html.