Hydrangea – a must for every garden

Hydrangea arborescens & Hydrangea ‘Lacecap’ at Kew Wakehurst.
Photo: Esther

Probably the most extensively grown and popular shrub in general garden cultivation today, the hydrangea makes a perfect subject for almost any position in  the garden.  Highly decorative and long flowering, each plant produces masses of bloom, and hydrangeas have remarkable powers of recovery, making them outstanding garden subjects.  They are also most useful as potted plants for patios and pool areas.

Hydrangea is derived from the Greek ‘hydro’ (water) and ‘angeion’ (vessel).  The name refers to the shape of the seed capsule of the first species discovered.  The diversity and range available today is not always appreciated.  These vary from dwarf varieties to shrubs, semi-climbers and even trees, and the colours are beautiful – white, all shades of blue, pink, red, carmine, purple and green.  Consequently they are ideal for ‘tying into’ any garden scheme.

Although species have been found in China, Korea, Formosa, Java, the East Indies, the Philippines, the Himalayas and the Americas, it is Japan we have to thank for the preservation and cultivation of this lovely flower.

The ancestral wild hydrangea, the Maritime species, grew on the seashores of Japan and many centuries ago gardeners took it into their gardens and cultivated it.  This species later became known as the ‘Lacecaps’ a delectable name for a lovely flower.

Hydrangea macrophylla at Kew Wakehurst – photo Esther

A ‘sport’ or freak seedling evolved from this species.  This had a large globose head composed entirely of the large, sterile flowers.  It was infinitely more striking and appealing to the eye and the Japanese quickly realised its potential.  They set out to cultivate and propagate this new variety, which was at the time, like its parent – quite unknown to the western world. Japan, one of the world’s riches storehouses of floral beauties, through a quirk of fate preserved some of our most exquisite garden flowers for over two centuries, during which period all foreigners, especially missionaries were prohibited from entering the country.

After a time Japan made rigidly controlled exceptions for the Dutch and Chinese as neither nations had ever sent missionaries into Japan and they were granted limited trading concessions.

The Dutch Trading Company employed three eminent physicians and botanists who made their way to Japan.  Engelbrecht Kaempfer (1651-1715) was a German, Carl Peter Thunberg (1775 – 1828) a Swede, and Dr. Philipp von Siebold (1791 -1866) was also a German.

It was Thunberg, more botanist than physician who was responsible for the introduction of hydrangea into Europe.  Thunberg, realising it was a new plant and noting its resemblance to dried plants he had named, confirmed it as Viburnum macrophylla – and so began the confusion over the name of the hydrangea that persisted for a very long period.

Over a period of years botanists gradually realised that the name Hydrangea hortensia, or Hydrangea macrophylla, covered a number of different types or species.

From the time the first hydrangea reached Europe until the present day, nurserymen have been actively engaged in the cultivation and improvement of the flower.

With December approaching look out for these beauties in your local garden centre.  The will provide a magnificent display in any garden over the Christmas period.  Hydrangeas as among the finest flowers for cutting and with care will last for weeks in the vase.

Hydrangea arborescens 
Photo: Esther

The count of species is debatable, from 23 to 80.  In Southern Africa  6 species are commonly found in the trade:

  1. Big leaf (H.macrophylla)
  2. Mountain (H.macrophylla ssp. Serrata}
  3. Lacecap (H.macrophylla normalis)
  4. Oak leaf (H.quercifolia)
  5. Climbling (H.petiolaris)
  6. Smooth (H.arborescens)
    Hydrangea serrata,  Hydrangea macrophylla and Hydrangea lacecap at Kew Wakehurst
    Photo: Esther

How to make your hydrangea bloom

A common problem that gardeners have is that their blooming can be unreliable. A plant that bloomed abundantly this year, may not bloom at all the next. Here are the three main reason why your hydrangea is not blooming.

  1. Too much shade – Hydrangeas prefer shade, but too much can reduce flowering. Bigleaf hydrangeas prefer more shade than panicle hydrangeas which prefer full sun.
  2. Improper pruning– Different hydrangea types flower on different years’ growths. Bigleaf and oakleaf hydrangeas flower on the previous year’s growth so if you prune them during autumn, winter or spring, you are removing potential flower buds. Panicle and smooth hydrangeas flower on the current year’s growth, so pruning in early summer would eliminate the potential flower buds for the year. The best time to prune these shrubs is immediately after flowering, before they begin their new season’s growth. Firstly, you must remove any dead material from the plant and all the old woody growth must be removed as close to the ground as possible. Finally, cut back all the old flower stems to just above a healthy bud
  3. Unfavourable weather– Most hydrangea species are highly sensitive to weather changes. For hydrangea types that flower on previous year’s growths, weather conditions that damage the plant during the autumn or winter can greatly reduce flowering in the summer.
    Hydrangea quercifolia

    Credits: By Any Other Name – The Story of Garden Flowers by Gladys Lucas