The Hydrangeas Flower
Decade after decade, hydrangeas remain one of the most beloved flowers in the garden. This versatile genus includes 75 species and hundreds of cultivars bred for their unique characteristics.
Today’s hydrangeas include rugged species that thrive in mountainous woodlands to engineered hybrids selected for their compact habit, strong stems, repeating blooms, incredible colors.
After centuries of domestication in western gardens, passionate plant breeders continue to develop new cultivars selected for their outstanding characteristics.
Hydrangeas belong to the Hydrangeaceae family, which is part of the order Cornales.
Several of the most popular species include:
- Hydrangea arborescens (Wild hydrangea)
- Hydrangea macrophylla (Bigleaf hydrangea).
- Hydrangea paniculata (Panicled hydrangea)
- Hydrangea paniculata 'Grandiflora' (Pee Gee hydrangea)
- Hydrangea quercifolia (Oakleaf Hydrangea)
- Hydrangea serrata (Mountain hydrangea)
The word hydrangea stems from two Greek words, hydro and ange, which mean water and vessel or receptacle respectively. Presumably, this literal translation refers to plant’s ability to thoroughly extract water from moist soil. However, others believe the name is due to the chalice-like shape of each flower.
Native to... (countries or continents)
Hydrangeas are found throughout continental Asia with unique species occurring in China, Japan, Korea, Indonesia, the Himalayas and Tibet. A limited number of species are native to North and South America, which makes them uniquely suited to the climate in the United States.
Many hydrangeas, including the mophead and lace cap hydrangea, have been cultivated in Europe for centuries leading to a deep association with this region. In fact, the alternate name Hortense was first coined by the French botanist Philibert Commercon.
Unfortunately, botanists later discovered the plant belonged to the existing order of hydrangea, but the name was so popular it’s still used by French gardeners today. Records of hydrangea cultivation in Europe date back to the 1700s. Specimens imported from China were added to England’s Kew Gardens as early as 1790.
Description and Characteristics
Hydrangea macrophylla also known as the bigleaf hydrangea, florist hydrangea or French hydrangea, is the most popular species. This diverse group includes more than 600 named cultivars encompassing both lace cap and mophead subtypes.
The genus also includes a number a lesser-known species, including Hydrangea anomala petiolaris or the climbing hydrangea, which is capable of winding 60 feet into the tree canopy.
With so many options, gardeners can choose hydrangeas based on their color, cold hardiness and habit. Here are a few of the most popular hydrangeas used across the country for their diverse characteristics.
Most hydrangeas are hardy between Zones 5 and 8 with some exceptionally rugged varieties, including the Annabelle hydrangea and the pee gee hydrangea, suitable for Zones 3 and 4.
Some of the all-time favorites and recent award-winners are from the macrophylla species. The newest generation of hydrangeas includes ever-blooming cultivars that flower on old and new wood for colorful blossoms all season. Twist and Shout, the Endless Summer hydrangea and All Summer Beauty and among the newest releases from Dr. Dirr of the University of Georgia, who is one of the preeminent hydrangea breeders today.
The pee gee hydrangea and the limelight hydrandgea from the paniculata genus are favorites with gardeners for their reliability, cold tolerance and ability to handle drastic pruning. The limelight is also popular with those who prefer green hydrangea flowers.
The popular Nikko Blue hydrangea is one of the most common cultivars. This cultivar reblooms in the fall and features exceptional blue or pink blossoms depending on the soil constituents. For those who prefer a purple hydrangea or a pink hydrangea, breeders have also developed cultivars, such as Alpen Glow and Glowing Embers, which feature brilliant magenta flowers.
Hydrangeas have been traditionally associated with beauty and vanity due to the abundance of showy petals. Over the years, hydrangeas have come to symbolize, love, devotion, gratitude and understanding, which has made the hydrangea a popular choice for the 4th anniversary as well as wedding ceremonies.
Cultivation and Care
Hydrangea plant care is minimal once specimens are established. Like any tree or shrub, hydrangeas require thorough watering and TLC after planting. To ensure trouble-free growth, plant hydrangeas at least four feet from the foundation of your home and other obstructions.
Hydrangeas require plenty of water. However, they don’t like wet feet. If you are planting hydrangeas in heavy, compacted soil or clay, adding pine bark and lightweight amendments can improve drainage and plant health.
Growing hydrangeas in full sun is preferred in Northern areas while Southern gardeners should select a location that provides partial shade. When planting or transplanting hydreangeas, it’s imperative to keep the soil at the same level. The best times to plant or transplant hydrangeas are fall, spring or early summer.
Planting during excessive heat can stress plants and hamper their success. For optimal growth, hydrangeas should be fertilized once in early spring after shrubs have leafed out and once in summer. If you are applying an extended-release fertilizer, shrubs may only require one fertilization.
With so many varieties and growth habits, many gardeners are stuck wondering, “When should I prune my hydrangea?” Pruning hydrangeas every year is not necessary. In most cases, pruning should be completed before August to avoid cutting off next year’s flowers.
During the winter, approximately 1/3 of branches can be removed to revitalize mature shrubs for the next season. On ever-bloomers, plants may be cut back to the ground at the end of the growing season.
Pruning hydrangea bushes back to the ground can be a practical solution. However, this method can prevent shrubs from growing the strong branches needed to support large flowers in spring.
Diseases and Pests
Hydrangeas are rarely bothered by pests and diseases. However, certain conditions can arise when plants are growing in unsuitable locations.
Hydrangeas are affected by:
- Powdery mildew
- Root rot
- Tobacco ringstops
- Spider mites
Hydrangeas are ideal for fresh and dried flower arrangements as well as bridal bouquets. To enjoy wilt-free hydrangeas, dip cut flowers in a cup of boiling water for 30 seconds before moving to a vase filled with cool water. Alternately, cut dip stems in the pickling agent alum before arranging.
To make dried hydrangeas, collect blossoms that have dried partially on the plant. Hang upside down in a dark, dry location for best results. Once flowers are dry, they can be colored by dipping in a liquid dye.
Hydrangeas contain cyanide and are toxic if eaten. According to historic accounts, Hydrangea paniculata has been smoked for its mood-altering affect despite the inherent toxicity.
In Asia, the leaves of the non-toxic species H. serrata are used to produce a sweet tea that is a vital part of annual ceremonies honoring the birth of Buddha. Native Americans also used the bark and roots of the endemic H. arborescense to treat kidneys stones and other ailments.
Blossom Color Changes
Most hydrangea macrophylla cultivars produce blue or pink flowers depending on the soil pH. To accentuate the blue hydrangea color, a small amount of aluminum sulphate and iron sulphate should be mixed with water and applied in spring and fall. To produce pink blossoms, raise the pH by adding lime.
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