Hydrangea, Blue   /   Hydrangea macrophylla

Geographic origins: China.
Adult dimensions: Height up to 1.5 metres, width up to 1 metre.
Foliage: Deciduous.
Soil type: Moist and well-drained. Enrich if too poor. Sensitive to lime.
Climate: Hardy down to -25°C.
Exposure: Partial shade to full sun.


Properties and uses:
The blue hydrangea is a must-have for shaded gardens and patios, blooming from May to October with glossy dark green foliage. It stands out for its pom-pom-shaped flower heads ranging from pastel blue to deep blue in acidic soil; they lean towards pink in neutral soil.
Ideal for flower beds, pathway borders, or low hedges along north- or east-facing walls, it also adapts perfectly to container growing. Highly valued in floral design, it creates long-lasting fresh bouquets or can be dried in autumn for timeless indoor decor.
Regular watering during summer is recommended, along with pruning spent flowers in early spring while keeping the buds just below to ensure current-year blooms.

Several varieties exist:
- 'Adria' hydrangea: compact and dense habit (around 1m x 1m), particularly early flowering.
- 'Renata Blue' hydrangea: height up to 1.5m.


Why is my blue hydrangea pink?
The blue colour of the hydrangea comes from aluminium binding to the petal pigments. Since aluminium is absorbed more easily in acidic environments, your soil may not be acidic enough.
Add peat, mulch with bark or pine needles, and apply alumina or Bleu de France® (watch the dosage!).
The more acidic the soil, the bluer or more purple the hydrangeas will be; conversely, in neutral soil, they will turn pink to red.