Flower of the Week: Bigleaf Hydrangea
Whether it’s planted in a garden bed or a patio pot, Bigleaf hydrangea is one of the most spectacular flowering shrubs that you can add to your landscape. With a long blooming season lasting from late spring into fall, and fragrant flowers in shades of blue and pink, Hydrangea macrophylla is a great choice for gardens large and small.
While bigleaf Hydrangeas can be challenging to grow successfully, their magnificent blooms make them a favorite of gardeners.
The two most common forms of bigleaf hydrangeas are Hortensia and Lacecap.
Hortensias have huge, showy mopheads of blooms, often in stunning shades of blue, and continue blooming throughout the summer and into the fall.
Flower of the hortensias
Lacecaps are more delicate in appearance, the clusters of blooms are flattened, with small flowerets in the middle, surrounded by larger, showier flowers that only last for about a month in summer.
Flower of the lacecaps
Originating in the woodlands of Japan, Big Leaf Hydrangeas have been cultivated in that country for close to two thousand years, and have long been one of the most beloved flowers in that country.
Hydrangeas in Kamakura
They were introduced to Europe in the eighteenth century by Carl Peter Thunberg, an employee of the Dutch East India Company, and in the nineteenth century the English plant explorer Charles Maries brought back some more varieties of bigleaf hydrangea from Japan.
Carl Peter Thunberg on a Sweden stamp
By the beginning of the twentieth century, the French were in the grip of a hydrangea craze, and their efforts to breed better hydrangeas led to the popularity of hydrangeas throughout the Western world in the 1900s, with no signs of letting up today.
Hydrangeas in France
France is home to the Shamrock Garden Hydrangea Collection in Normandy, with 5 acres of hydrangeas, and in July and August, the island of Faial in the Azores has thousands of deep-blue hydrangeas in bloom.
Hydrangeas feature prominently in Japan’s culture, where they are called Ajisai. Annual Ajisai festivals celebrate the blooming season of hydrangeas in June and July, and tea brewed from Hydrangea serrata leaves, called “amacha” or “tea from heaven”, is customarily drunk on Buddha’s birthday on April 8.
Floating hydrangea in Meigetsuin temple, Kanagawa
In its home country of Japan, the blue hydrangea symbolizes deep emotion and contrition. Legend has it that an emperor gave blue hydrangeas to the family of the woman he loved as an apology for neglecting her. Also in Japan, pink hydrangeas are a traditional gift on a fourth wedding anniversary. Meanwhile, in Victorian England, white hydrangea blossoms symbolized arrogance and coldness when given to women who rejected suitors.
Hydrangeas are famous for their brilliant blue flowers, which depend on aluminum in acidic soil; otherwise, they revert to shades of pink and cream. There are hundreds of varieties available.
Hydrangea macrophylla ‘Glowing Embers’ produces red-pink mopheads in summer. Hydrangea macrophylla ‘Penny Mac’ has deep blue mopheads from July to October. Hydrangea macrophylla ‘Bailmer’ produces magnificent blue mopheads from June through to October; it’s very hardy and will bloom on old or new wood, making it a great choice for beginners.
Glowing embers hydrangea
One of the most fascinating things about Hydrangeas is that you can alter the color of the blooms by adjusting the soil pH. If you want blue flowers, you need to give your Hydrangea acidic soil full of organic matter, as the soil should be kept moist but well-drained. The other key to blue blooms is aluminum in the soil, which can only be taken up properly when the pH is low. You can add aluminum supplements in either granular or liquid form to encourage brilliant blue blooms.
If you prefer your hydrangeas in shades of pink, you need to raise the pH, which can be done with lime.
Hydrangeas require careful siting and soil preparation to get the best blooms possible. These plants originated as understory shrubs in the forests of Japan, so it’s best to give them some shade, especially in hot climates. They will thrive with morning sun and afternoon shade. It’s also a good idea to avoid a south or west exposure, as the buds might open too early in those warmer spots, thus risking getting nipped by a late spell of cold weather.
Only prune Big Leaf Hydrangeas immediately after their blooms have faded, as most varieties bloom on old wood. Avoid any pruning after August 1, since next year’s flower buds form in late summer and fall.
Small varieties of bigleaf hydrangeas are perfectly suited to container cultivation, where you can more easily control the pH of the soil. Larger varieties can be grown as single specimens, or as an informal flowering hedge.
Size: 1-1.5 m (3-6 feet) height and spread
Hardiness: USDA Zone 5-9
Sunlight: Morning sun and afternoon shade
Soil: Moist but well-drained acidic to neutral pH soil
Bloom Time: late spring to fall