How to Get Purple Hydrangea Blooms by Adjusting Soil pH

Purple hydrangea flowers result from intermediate soil pH between pink (alkaline) and blue (acidic). Start with a pink-leaning cultivar like 'Cardinal Red', 'Ami Pasquier', 'Alpenglow', or 'Pia'.

Two-Year Regimen

1. Spring: Drench with 2 Tbsp aluminum sulfate per gallon water.
2. Spring: Scatter ¼ cup powdered sulfur under the plant.
3. Repeat both steps for two years.

Flowers shift to purple. If not, continue sulfur only—excess aluminum can be toxic.