Did you know? Hydrangea Day is celebrated on the 5th of January every year.

Of all the plants... the Endless Summer (Hydrangea macrophylla) has generated the most volcanic enthusiasm - Michael Dirr, the author of 'Manual of Woody Landscape Plants'.

Hydrangeas are one of the most beautiful flowers. Inflorescence in the genus Hydrangea comes in groups. Hydrangea has long been a popular flowering shrub. The flowers are considered by many as Grandmother's old-time flower.


Hydrangea is a genus of about 100 species of flowering plants native to southern and eastern Asia (from Japan to China, the Himalaya and Indonesia) and North and South America. Hydrangeas produce flowers from early spring to late autumn. The flowers of Hydrangea are carried in bunches, at the ends of the stems. Each individual Hydrangea flower is relatively small. However, the display of color is enhanced by a ring of modified bracts around each flower.

In most species of Hydrangea the flowers are white, but in some species, can be blue, red, pink, or purple. In Hydrangea species the exact color often depends upon the acidity or alkalinity of the soil. Acidic soils produce blue flowers, neutral soils produce pale cream petals, and alkaline soils result in pink or purple.

  • Hydrangeas are one of very few plants that accumulate aluminium. Aluminium is released from acidic soils, and forms complexes in the hydrangea flower giving them their blue color.
  • Hydrangeas produce their main flower clusters from the tips of shoots formed from the previous season.
  • If the terminal buds of these shoots are destroyed, the plant usually fails to bloom. The chief causes of destruction of the terminal buds are excessive winter cold and uninformed pruning.
  • Hydrangeas are also widely used as dried flowers, especially the blue Hydrangeas.
  • The Japanese refer to these Hydrangea plants as Mountain Hydrangeas because they originate in the mountainous areas on the islands of Japan. These hydrangeas are smaller in stature and have smaller leaves and delicate lacecap flowers.
  • Although most Hydrangeas bloom in summer and fall, a few Hydrangeas have developed the ability to set new bloom buds in the spring after the old ones have been pruned off or damaged.
  • Endless Summer is just such a hydrangea. This trait is referred to as being "remontant".

There are 3 types of flower blooms in Hydrangea. They are -
Mophead - Globe shaped flower cluster, the most commonly recognized form of Hydrangea bloom.
Panicle - Long, somewhat cone-shaped flower cluster (particularly in Oakleaf Hydrangeas).
Lacecap - Flattened cluster of what appear to be tiny, immature buds surrounded at the edges by typical 4 to 5 petal flowers.

Further, there are many varieties of Hydrangeas. Some of the most popular varieties are tabulated below -

Common Names Scientific Names Uses
Bigleaf Hydrangea,
Garden Hydrangea,
Endless summer,
French hHdrangea,
Common Hydrangea
Hydrangea macrophylla The leaves, roots and flowers are antimalarial, antitussive and diuretic. They are said to be a more potent antimalarial than quinine.
Oakleaf hydrangea,
Snow Queen
Hydrangea quercifolia Can be used as a specimen plant where space is adequate, or as an untrimmed hedge or background where screening is desired.
Peegee hydrangea Hydrangea paniculata Grandiflora The flowers contain up to 4.06% rutin, which makes them useful for reducing the incidence of recurrent haemorrhages associated with increased capillary fragility, particularly in hypertension.
Smooth Hydrangea Hydrangea arborescens Annabelle The flowers are sweetly scented.
Climbing Hydrangea Hydrangea anomala petiolaris A boiled concoction of the leaves is used to make a syrup. The sweet sap is used as a drink.
  • Propagation of Hydrangeas is rather easy with cuttings obtained from the ends of non-flowering shoots with two or three pairs of leaves, from April to August.
  • Hydrangeas are easy to grow in well-drained soil, which should contain plenty of organic matter or humus.
  • It is best to root them in sand in a shaded area. Avoid planting it in hot, dry, exposed sites.
  • For planting, dig a large hole approximately two feet across and one foot deep.
  • Only the Hydrangeas which naturally have pink flowers will bloom blue, if grown in an acidic soil.
  • Hydrangea plants grow without difficulty in a wide variety of soils but prefer fairly rich moist soil.
  • A general-purpose fertilizer, such as 10-10-10 applied at a rate of 2 cups per 100 square feet in March, May and July is suggested.
  • It is not necessary to remove the mulch when fertilizing, but water soon after application to help dissolve the fertilizer and send it into the soil.
  • Hydrangeas can grow in full sun if they are watered well, but will bloom more freely in partial shade.
  • White blooms will always be white, while the blue or pink can be controlled by the pH of the soil (the closer to a balanced pH of 6.5, the lighter the color).
  • Hydrangeas need plenty of water, so plan to water thoroughly once per week or more frequently.
  • Pruning is the most essential factor in the growth of Hydrangeas. Since the flowers appear on previous year's growth, prune only the stems that produced this year's flowers; otherwise you will not have blooms next year.
  • In severe cold winter weather they should be covered. Pruning should be done in summer as soon as the flowering season is over.
  • When pruning, all the old flowering shoots should be removed down to the point on the stem where strong new growth is developing. If you want flowers, do not prune in late fall, winter or spring.

Dr. Michael A. Dirr is a professor at the Department of Horticulture, University of Georgia. His lifelong passion for horticulture has positively influenced a generation of students, gardeners, nursery- men, and professional horticulturists. Dirr's "Manual of Woody Landscape Plants" is the leading horticultural text and reference work, and, along with his Reference "Manual of Woody Plant Propagation", has become the "Bible" for the landscape and nursery industry.

He is popularly known as the Hydrangea Guru for his exceptionally great research on Hydrangeas. Dirr's Plant Introduction Program has con- tributed over 50 new plant introductions to the Green Industry. He developed Lady in Red, a variety of Hydrangea macrophylla. It is the first patented release from the University's "Continued Adventures in Plant Improvement in the Department of Horticulture and Center for Applied Nursery Research" program, headed by Dr. Dirr.