Test the soil pH
For blue flowers, lower the soil pH
Add aluminum sulfate to acidify the soil
Use sulfur or peat moss to gradually lower pH
Water with rainwater if possible
For pink flowers, raise the soil pH
Add garden lime to increase pH
Avoid aluminum sulfate if you want pink flowers
Keep the soil consistently moist
Apply amendments slowly and retest the soil regularly
Use a hydrangea variety that changes color naturally
Follow the plant’s specific color response to pH