How to Get Blue Hydrangeas: Adjusting Soil pH for Color

Hydrangeas are the mood rings of the garden—their flower color reflects soil pH. Only bigleaf (H. macrophylla, mopheads and lacecaps) change color; oakleaf and ‘Annabelle’ stay white/cream.

1. Choose a Blue‑Bred Variety

Look for ‘Nikko Blue’, Endless Summer ‘The Original’, ‘Blue Danube’, ‘Penny Mac’, ‘Blauer Prinz’, Endless Summer ‘Twist‑n‑Shout’. Plant tags show bloom color if not in flower.

2. Test Your Soil pH

pH scale 0–14; 7 is neutral. <7 = acidic, >7 = alkaline. Use a soil test kit.

3. Target pH for Desired Hue

• True blue: pH 5.5 or lower (acidic)
• Pink: pH 6.5 or higher (neutral to alkaline)
• Purple/mixed: pH 5.5–6.5

4. Adjust the pH

To lower pH (blue): add sulfur, sulfate, or products like Bailey’s Color Me Blue (soil sulfur). To raise pH (pink): add garden lime (Bailey’s Color Me Pink). Mix into soil at planting.

5. Maintain the pH

Soil pH drifts; work acidifiers into the top layer around the root zone regularly to keep blooms blue.