The hydrangea is a garden favourite for its enormous, billowing clusters of flowers in blue, pink, purple, and white. Famously, the color of some hydrangeas can be changed by the soil — a bit of garden chemistry that makes them endlessly fascinating.

Hydrangea at a glance

• Botanical name: Hydrangea macrophylla
• Family: Hydrangeaceae
• Bloom season: summer to autumn
• Symbolism: gratitude, grace, and heartfelt emotion

About the hydrangea

Hydrangeas are shrubs that bloom from summer into autumn, carrying their tiny flowers in large rounded ‘mophead’ or flatter ‘lacecap’ clusters. In bigleaf hydrangeas, flower color depends on soil pH: acidic soil turns blooms blue, while alkaline soil turns them pink, thanks to how the plant takes up aluminum.

Hydrangea meaning and symbolism

The hydrangea symbolizes gratitude, grace, and heartfelt emotion, though it has also carried a meaning of boastfulness in some traditions. Explore more flower meanings.

Types of hydrangea

Popular varieties worth knowing:

• Bigleaf (mophead & lacecap) — the color-changing classic
• Panicle — cone-shaped blooms, very hardy and sun-tolerant
• Smooth (‘Annabelle’) — huge white rounded heads
• Oakleaf — oak-shaped leaves with great fall color
• Climbing hydrangea — a vine for walls and fences

How to grow and care for hydrangea

A few essentials keep this flower thriving:

• Give morning sun and afternoon shade in most climates
• Keep the soil consistently moist and well-drained
• For blue blooms, acidify the soil; for pink, add lime
• Prune according to type — timing varies, so know your variety
• Mulch to conserve moisture and protect roots

Hydrangea FAQs

How do you change a hydrangea’s color?

In bigleaf hydrangeas, acidic soil (lower pH) produces blue flowers and alkaline soil (higher pH) produces pink. You can shift the color by amending the soil with aluminum sulfate for blue or lime for pink.

Why won’t my hydrangea bloom?

Common causes are pruning at the wrong time (cutting off next year’s buds), late frosts, too much shade, or too much nitrogen fertilizer, which favors leaves over flowers.

Do hydrangeas need sun or shade?

Most hydrangeas do best with morning sun and afternoon shade. Panicle hydrangeas are the most sun-tolerant, while bigleaf types prefer more shade in hot climates.

Explore more

Browse more flower profiles, learn about flower meanings, or find your birth flower.