Changing the Color of Your Hydrangeas
A Simple Guide for New Gardeners
As gardening enthusiasts, we often find ourselves captivated by the ability of hydrangea flowers to change their color. Many of the color-adjustable Endless Summer (and other) varieties, which we stock at The Family Tree Garden Center, allow you to control the bloom colors of your hydrangeas. This unique characteristic is highly dependent on the pH of the soil, and with some simple adjustments, you can change the color of your hydrangea blooms from pink to blue or vice versa. But how does this color change work precisely, and what can you do to influence it? Here's a step-by-step guide to understanding and adjusting the color of your hydrangea blooms.
Our BloomStruck®️ Big Leaf Hydrangeas by Endless Summer can have either vivid rose pink or blue-purple flowers depending on your soil pH.
Understanding the Color Change
Before we get into the steps, it's important to understand what makes this color change possible. Certain types of hydrangeas, notably the Bigleaf varieties (Hydrangea macrophylla), which include the Endless Summer series, change color based on the availability of aluminum in the soil. Aluminum, naturally present in many soils, becomes available to the hydrangea's root system when the soil is acidic, that is when the soil pH is low.
When the soil is acidic (pH below 7), hydrangeas take up aluminum, leading to blue flowers. On the other hand, when the soil is alkaline (pH above 7), the aluminum becomes locked in the soil, and the hydrangeas can't absorb it, which results in pink flowers. White hydrangeas, however, are not affected by soil pH and will always bloom white.
How to Test Your Soil's pH
Collect a Soil Sample: Using a trowel, collect soil from around the base of your hydrangea, from just below the surface to about four inches deep.
Test the Soil pH: You can use a home testing kit, available at our garden center, to determine the pH of your soil. Follow the instructions provided with your kit or tester.
How to Adjust Your Soil's pH
Once you know your soil's pH, you can take steps to adjust it. If you want to turn your hydrangeas blue and your soil is alkaline, you'll need to lower the pH. If you want to turn your hydrangeas pink and your soil is acidic, you'll need to raise the pH.
For Blue Hydrangeas: Lowering Soil pH
Add a Soil Acidifier: To lower the pH, add a soil acidifier, such as aluminum sulfate or sulfur, to your garden. We recommend using Espoma Organic Soil Acidifer (look for the blue bag in our fertilizer department). These can be found in our garden center (ask one of our plant pros for assistance). Follow the package instructions for application rates and methods.
Water Thoroughly: After applying the acidifier, water your hydrangeas thoroughly to help them penetrate the soil and reach the roots.
Monitor the pH and Color: Continue testing the soil pH every few weeks and watch for a color change in the blooms. You may need to apply the soil acidifier several times throughout the growing season to maintain the desired pH level.
Espoma Organic Soil Acidifier
If your soil test shows that you have a pH above 7, then add Espoma Soil Acidifer to turn your hydrangeas blue. Look for the blue bag in our fertilizer department!
For Pink Hydrangeas: Raising Soil pH
Add Lime: To raise the pH, add garden lime to your soil. We recommend using Espoma Organic Garden Lime (look for the lime green bag in our fertilizer department). Again, follow the package instructions for application rates and methods.
Water Thoroughly: After applying the lime, water your hydrangeas thoroughly.
Monitor the pH and Color: Keep testing the soil pH every few weeks and watch for a color change in the blooms. You may need to apply lime several times throughout the growing season to maintain the desired pH level.
Espoma Organic Garden Lime
If your soil test shows that you have a pH below 7, then add Espoma Garden Lime to turn your hydrangeas pink. Look for the lime green bag in our fertilizer department!
A Gentle Word of Caution
While changing the color of your hydrangeas can be a fun and rewarding gardening project, it's important to be patient and not overdo it with soil amendments. Changing the soil pH too drastically or too quickly can harm your plants. And remember, hydrangeas will only change color in response to pH adjustments over time, and not all varieties can change the color of their blooms, so feel free to ask our plant pros when selecting your hydrangeas.
At The Family Tree Garden Center, we're here to help you every step of the way. From selecting the perfect hydrangea variety to providing the tools and guidance to adjust your soil's pH, we're committed to helping you achieve your gardening goals. So why wait? Start experimenting with your hydrangea colors today!
Happy hydrangea gardening!
