So you bought and planted a "blue" Hydrangea when it wasn't blooming and when it first bloomed in your gardens were surprised to see that the flowers were pink. No worries. With the tips below you can change the color to blue! Read on to find out why hydrangeas will sometimes bloom different colors and how you can easily change the color.

Hydrangeas are happy growing in moderately acid to moderately alkaline soils ranging between 5.0 to 8.0 on the pH scale. This is great for two reasons. One, because hydrangeas perform well in such a wide range of pH, it means there's usually not a need to adjust soil pH to make them happy. Two, because it allows you a wide range for adjusting soil pH, which can change the flower colors on the specific Hydrangea species.

Though the color of white-flowering hydrangeas cannot be changed, with an adjustment to the soil, specifically the soil pH, most other colors can be changed. An acid soil typically produces blue or purple flowers while an alkaline soil produces pink or even red flowers. A slightly acid or neutral soil can produce purple flowers or a mix of blue and pink on a the same shrub. For example, you could purchase and plant a hydrangea with blue flowers on it this year. Then, next year, the same plant produces pink flowers. This would indicate alkaline soil conditions in your garden soil. Therefore, you'd need to adjust the pH so that the soil becomes more acid.

How To Change Soil pH

Changing soil pH is done with the application of specific soil additives. To change the flower color of your Hydrangea follow the guidelines below.


Soil additives, such as aluminum sulfate or soil sulfur lower soil pH, making it more acidic, changes hydrangea flowers from to blue and purple shades. Follow instructions on product label for application rates. Mulching with organic compost or adding it to the soil can help to increase soil acidity and maintain acid soil conditions. 


The application of a fast-acting pelletized lime or agricultural limestone changes hydrangea flower color from blue to pink or purple, apply a fast-acting pelletized lime.

Note:  Keep in mind that the color changing process can take two or more growing seasons to accomplish. Adjusting acid soil to alkaline doesn't seem to take as long as from alkaline to acid. 

Hope this information is helpful. If you need more details don't hesitate to contact us.

Plant Long & Prosper!

Related Articles

Questions? Contact us