Hydrangea Color Control: Soil pH and Aluminum Management

Achieving Blue or Pink Blooms

A Southern California gardener's hydrangeas have greenish-pink flowers, wants true blue or pink.

Soil Chemistry Determines Color

• Blue flowers – pH 5.0-5.5 + available aluminum
• Pink flowers – pH 6.0-6.5
• Test soil first – Determine current pH
• Aluminum-containing fertilizer – For blue coloration

Color manipulation requires soil testing and targeted amendments.