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How to Change the Color of Your Hydrangeas

Hydrangeas are prized for their ability to produce blooms in various colors, from vibrant blues to soft pinks and even shades of purple. Did you know that you can influence the color of your hydrangea blooms? With a few simple techniques, you can manipulate the soil pH to achieve the desired hue. Whether you prefer the cool tones of blue or the warm blush of pink, understanding how to adjust soil acidity or alkalinity will help you create a stunning display of colorful hydrangea blooms in your garden.

Tips for Changing Hydrangea Bloom Colors

1. Understand the Role of Soil pH

The color of hydrangea blooms is directly influenced by the pH level of the soil. Acidic soil (low pH) produces blue blooms, while alkaline soil (high pH) results in pink blooms. Neutral soil pH (around 7.0) typically yields purple blooms, though this can vary depending on the specific hydrangea variety.


2. Testing Soil pH

Before making any adjustments, it’s essential to test your soil pH using a soil testing kit available at garden centers or through your local cooperative extension office. This simple test will indicate whether your soil is acidic, neutral, or alkaline.

3. Adjusting Soil pH for Blue Blooms

  • Aluminum Sulfate: To achieve blue hydrangea blooms, lower the soil pH to a range between 5.2 and 5.5. This can be done by adding aluminum sulfate to the soil around your hydrangeas. Follow package instructions carefully to avoid over-application.

4. Adjusting Soil pH for Pink Blooms

  • Garden Lime: For pink hydrangea blooms, raise the soil pH to a range between 6.0 and 6.2. Use garden lime (calcium carbonate) to increase alkalinity in the soil. Again, follow manufacturer guidelines to apply the correct amount for your soil type and plant needs.

5. Applying Amendments

  • Timing: It’s best to make soil pH adjustments in the fall or early spring before new growth begins. This allows the amendments to integrate into the soil gradually and affect the upcoming bloom season.
  • Even Application: Spread the chosen amendment evenly around the base of your hydrangeas, avoiding direct contact with the stems. Water lightly after application to help the amendments penetrate the soil.

6. Monitoring and Maintenance

  • Regular Testing: Periodically check the soil pH to ensure it remains within the desired range for your preferred bloom color.
  • Adjust as Needed: Depending on environmental factors and soil composition, you may need to reapply amendments to maintain the desired pH level over time.


Changing the color of your hydrangea blooms is an enjoyable way to personalize your garden’s aesthetic. By understanding how soil pH influences bloom color and applying the appropriate amendments, you can transform your hydrangeas into a captivating display of blues, pinks, or purples. Experiment with different varieties and techniques to achieve stunning results and enjoy a season filled with vibrant hydrangea blooms.



1. How long does it take for hydrangea bloom color to change after adjusting soil pH? It may take a full growing season for the effects of soil pH adjustments to become visible in hydrangea blooms. Be patient and monitor plant health and growth throughout the process.

2. Can I change the color of all hydrangea varieties? Most hydrangea varieties, particularly Bigleaf hydrangeas (Hydrangea macrophylla), respond well to soil pH adjustments for changing bloom colors. Other varieties, like Panicle hydrangeas (Hydrangea paniculata), generally produce white or cream-colored blooms that do not change with soil pH.


3. Will adjusting soil pH harm my hydrangeas? When done correctly and in moderation, adjusting soil pH with aluminum sulfate or garden lime should not harm your hydrangeas. Follow application guidelines carefully and monitor plant health for any signs of stress or nutrient deficiencies.

4. Can I revert the bloom color back to its original shade? Yes, you can adjust soil pH again in subsequent seasons to revert hydrangea bloom color to its original shade or change it to a different color. Monitor soil pH closely and make adjustments as needed based on your color preferences.


5. What other factors besides soil pH can affect hydrangea bloom color? In addition to soil pH, factors such as plant genetics, environmental conditions (temperature, sunlight), and soil composition (nutrient levels) can influence hydrangea bloom color. Consider these variables when planning and maintaining your hydrangea garden.



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