Big Leaf Hydrangea - Hydrangea macrophylla

Hydrangea macrophylla is the quintessential cottage garden shrub, beloved for its lush green foliage and spectacular mophead or lacecap flowers that bloom in shades of blue, pink, purple, red, and white from summer through to autumn. One of its most fascinating qualities is that flower colour can be influenced by soil pH, with blue flowers appearing in acidic soils and pink or red tones in alkaline soils, while white-flowering varieties remain white regardless of conditions. Growing to approximately 1.5m tall and 1m wide, it is a classic choice for garden beds, shady borders, and large containers.

With a naturally rounded, clumping habit and thick, glossy green leaves, Hydrangea macrophylla suits a wide range of garden styles from formal to relaxed cottage. It thrives in full sun, semi shade, and full shade, and makes an outstanding cut flower both fresh and dried. Keep moist during dry periods, mulch well, and feed annually with a slow-release fertiliser for the most impressive flowering display each season.

Key Features:

• Soil: Prefers loam, sandy, and well-drained soils enriched with organic matter. Soil pH influences flower colour, with acidic soils producing blue flowers and alkaline soils producing pink or red tones.
• Light: Thrives in full sun, semi shade, and full shade. Afternoon shade is beneficial in hot climates to prevent leaf scorch.
• Watering: Keep moist during dry periods as Hydrangea macrophylla has low drought tolerance. Water deeply and regularly through summer and autumn to support healthy foliage and flowering.
• Fertiliser: Apply an annual slow-release fertiliser in spring to support healthy growth and prolific flowering. To encourage blue flowers, apply a soil acidifier. To encourage pink flowers, apply a soil alkaliser.
• Maintenance: Low maintenance overall. Mulch well around the base to retain moisture and keep roots cool. Prune lightly after flowering, removing spent flower heads and any dead or weak stems to encourage fresh growth the following season.
• Flowering: Large mophead or lacecap flowers in blue, pink, purple, red, or white appear from summer through to autumn. Flower colour is influenced by soil pH.

To change or intensify the flower colour of your Hydrangea macrophylla, amend the soil pH before the growing season begins. Apply aluminium sulfate to acidify the soil for deeper blue flowers, or add garden lime to raise the pH for richer pink and red tones. Start with small amounts and test the soil regularly to avoid overcorrecting.

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