Q: Can you really change the color of hydrangeas? I have a pink one in a pot, but I'd love to make it blue. What can I do?
A: Yes, you can change pink flowers to blue and vice versa with certain hydrangea varieties: Hydrangea macrophylla and Hydrangea serrata. This process is all about the soil type, which can be manipulated with some know-how.
Below, gardening experts break down the science behind this fascinating change and provide tips on how to achieve it while growing hydrangeas at home.
Hydrangeas are cherished for their beautiful blooms.
Tips from Experts on Changing Hydrangea Colors
Whether you're growing hydrangeas in containers or in garden beds, these insights will help you manage or alter their color.
Understanding Why Hydrangea Flowers Change Color
Soil pH adjustments can influence the color of your hydrangeas.
Hydrangea colors shift based on aluminum levels in the soil, as explained by a gardening expert. The pH of the soil is crucial, as aluminum ions are only available in acidic conditions.
'To achieve blue flowers, ensure both aluminum is mobile and the soil is acidic,' she states. Aim for a pH below 6.0 for blue blooms.
If the pH exceeds 7.0, the soil becomes alkaline, leading to pink or red flowers. Intermediate pH levels typically result in purple blooms, a blend of blue and pink.
Kristen has worked in the new product department since 2011, currently managing the woody ornamental portfolio.
Steps to Alter Your Hydrangea's Flower Color
Acidic soil encourages blue hydrangea flowers.
'Start with soil testing if you want to change your hydrangea blooms' color,' advises a nursery owner. You can find soil pH testers on Amazon that also measure moisture and light.
Once you know your soil's pH, you can adjust it to achieve your desired flower color.
To get blue flowers, you'll need acidic soil. The best acidifier is aluminum sulfate, which lowers pH and adds aluminum. You can also use garden sulfur to achieve a lower pH.
Another expert suggests using organic, acidic mulch like pine needles to maintain lower pH levels. If your hydrangea is in a pot, consider a soil mix designed for acid-loving plants, like Coast of Maine's mix available on Amazon.
For pink flowers, add garden lime to raise the pH. This garden lime from Jobe's Organics on Amazon is a popular option.
Bonide Aluminum Sulfate can also be used in any soil to lower pH and encourage blue hydrangeas.
Timeframe for Changing Hydrangea Flower Color
Transforming your hydrangeas' colors takes time; expect several months for changes.
One expert notes that certain areas may have soils heavily leaning toward acidic or alkaline, making it challenging to change hydrangea colors, potentially requiring multiple seasons for successful pH adjustment.
Regular soil pH testing is essential to ensure it stays within the ideal range for your desired hydrangea color.
Do White Hydrangeas Change Color with Soil pH?
White hydrangeas, like Annabelle, are popular and stunning in various garden styles. They do not change color based on soil pH. However, some varieties, like Bobo® panicle hydrangeas from Nature Hills, may develop a pinkish hue as they mature.
Need more tips for your hydrangeas? Check out our guides on pruning hydrangeas and watering hydrangeas for practical advice.
