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The Queen of the Tropics

by Irmtraud Gotsis
The Mediterranean Garden No 38 July 2004

After the rainy season when the sun regains its strength, the countryside of the south-west Peloponnese reawakens with its rich greenery against the bright blue of the spring sky. Before too long the bright red flowers of the hibiscus - their 'eyes' often pitch-black - nod among the glossy foliage of their large bushes. The 'Mediterranean' hibiscus (Hibiscus rosa-sinensis) has been found in the gardens of the western Peloponnese, the Greek islands and the mainland for the past 40 years. In Messinia, the south-west corner of the Peloponnese, it has found almost ideal conditions: soil with a pH value of 6-7 and high humidity in the air, thanks to the dense olive groves, which is further increased by the juxtaposition of sea and mountains and by the high annual rainfall.

When I started gardening here twenty years ago I was amazed at the ease with which this plant could be propagated by cuttings. I shall never forget how once, in search of a stick to support a gladiolus, I cut off a straight branch from a hibiscus bush. After the gladiolus flowers were long gone and the mice had eaten the corms, my stick has produced leaves and soon became another hibiscus plant.

During recent winters night temperatures have often fallen to minus 3 to minus 5 degrees Celsius. In two winters the temperature even dropped briefly to minus 8 degrees, while last winter saw a severe frost in the morning, which had never been the case before. Yet with heavy cutting back, the hibiscuses that had suffered frost damage appeared again like the phoenix from the ashes and produced rich blooms by the end of spring. Moreover, old hibiscus plants, trained to grow as trees, are planted along the lanes of our village; they can support a great deal of dryness, annual cutting back, exhaust fumes etc. They also tolerate being near the sea fairly well. Certainly the cold winds of winter with their heavy salt spray can cause damage and the bushes often lose all their leaves. However, the plants survive and start afresh with the first warm rays of the sun.

In their native tropics hibiscuses are normally in bloom throughout the year. Here, their flowering season is limited to spring and autumn. The hibiscus produces its blooms at temperatures of between 18 and 25 degrees Celsius. This is why in our climate, where summer temperatures reach 35 degrees or more, it does not flower in summer. On the other hand, the many shining red flowers produced in October, as the gardening year comes to an end, are of particular beauty. Even the heavy rains that set in at this time of year do not stop them - quite the contrary, as long as the temperature remains clement.

After many years of observation, I can say that this hibiscus with its single red, dark-centred flower supports the mediterranean climate very well. It grows well in pots and makes a focal point for any terrace. In particularly dry areas, spraying the plants with the garden hose has proved helpful.

Naturally, it is cold winters that time and again give us problems with this plant. After ten years of growing Hibiscus rosa-sinensis I have to say that planting it out in the garden always involves a risk. If one wants to do so anyway, then I recommend first taking cuttings 15-20cm long with several eyes from branches of second growth (one or two years old) and planting them to the depth of two eyes in garden soil in not too small plastic cups. This way, in case of catastrophe, at least one does not lose the entire plant.

Growing hibiscuses in pots has many advantages. We can use them as a decorative element on balconies and terraces, can shelter them from the strong summer heat and can move them inside to protect them from cold winds and frost in winter. During good weather they are grateful for the winter sun. This may seem like a lot of trouble, but their beauty is an ample reward. A heated conservatory, of course, would be the ideal solution since here the Queen of the Tropics would flower in winter as well - but how many of us possess such a thing? In my own garden the many hibiscus plants survive the winter under the protection of dense evergreen bushes; since one has to cut them back in spring anyway, a few branches damaged by frost are no problem.

Plants in pots need fertiliser. A golden rule: 'a great deal' is not a great help. It is better to give little more often, for example twice a week dissolved in the water the plant receives. I have had good results with COMPO Hakaphos 20-19-19.

Occasionally the leaves start to become yellow between the ribs. This indicates a lack of iron and can be remedied with an appropriate dose of iron. Please protect our health and don't use insecticides if infestation with white spider, spider mites or aphids makes you panic: instead, try to avoid too much concentrated heat by placing the pots where they receive a breeze, and hose down the plants to wash off aphids. Alternatively, you can spray the plants with Neem Oil, an organic preparation.

When we buy hibiscuses they are usually planted in peat. In our climate this dries out easily and, as a result, cannot absorb water which simply passes through the pot without benefiting the plant. When this happens, plunging the whole pot in water for a while may sometimes help, if you are lucky. It is better, however, to repot the newly-bought plant straight away in a fresh mixture of loamy garden soil with a bit of potting compost. It is known that a mixture of sand and loam conserves humidity better while at the same time allowing good drainage. To protect the surface of the soil from too much sun and to avoid a crust forming on top, we can cover it with cut grass or other mulching material. It is better to cut off weeds with a sharp tool rather than pull them out.

So much for the cultivation of hibiscuses. When I started growing the so-called 'Mediterranean' hibiscus many years ago I was so fascinated that I tried to find out more about it. Gardening books list it as Hibiscus rosa-sinensis. Its origins are uncertain but since it is believed to come from China it is also sometimes referred to as Hibiscus chinensis. Moreover, some texts state that it is a hybrid. The American Hibiscus Society (AHS), based in Florida and founded in 1950, provided some clarification. I quote from the AHS Handbook:

"The ornamental hibiscus of our gardens is commonly - but incorrectly - thought of as being derived from a single species, Hibiscus rosa-sinensis. The first plants known to westerners were double-flowered forms imported to England and Europe from China, Java and India in the early 1700s. Later, some single-flowered forms were also imported. When referring to ornamental hibiscus as H. rosa-sinensis, taxonomists cite as their authority Linnaeus' Species Plantarum (1753). The type he referred to was probably the double red which had a wide distribution throughout China, India, South-East Asia and the Pacific Islands in pre-European discovery days. Later a single red form was included in the taxonomic treatment of this hibiscus.

Prior to 1900, a few of these 'old' hibiscus hybrids, and some compatible species, had been introduced to Hawaii. In 1902 the first hybrids were made in the island. Shortly thereafter, the scented white-flowered natives H. waimeae and H. arnottianus and forms of the red-flowered H. kokio were being crossed with the imported plants and with the resulting progeny. Unexpectedly, a whole new race of hybrids with larger, longer-lasting flowers arose. This race of ornamental plants became known world-wide as the Hawaiian Hibiscus.

This work has clearly indicated that the ornamental hibiscus designated as H. rosa-sinensis is in reality a highly polymorphic group composed of complex hybrids and their derivatives. While its hybrid origin and the subsequent range of colour and form which may be produced from one cross heighten the interest in hybridizing as a garden hobby, it also suggests to the taxonomist that [the plant] should now be referred to as Hibiscus x rosa-sinensis to represent properly its hybrid nature."

Incidentally, in the summer of 2002 our local flower shops began to offer so-called mini hibiscus plants. These are in fact hibiscus hybrids which have been treated when small with Chlorcholinchloride - Cycocel - which stunts growth. The result is apparently dwarf plants with blossoms of the original size. Dwarfing methods of this kind, used so often for decorative plants, are not necessarily liked by plant lovers. In any case, here in the south, as soon as the effects of the Cycocel wear off, the plant returns to its natural growth pattern. The plants I bought in 2002 have grown well over the past year, are healthy and in bloom.

In twenty years of growing these plants, I have never seen a ripe seedpod on my different Hibiscus rosa-sinensis. I accepted this fact without understanding it, imagining that, as a tropical plant, the hibiscus was unable to find the right insects for pollination in our climate. Once again, the AHS enlightened me:

"Hibiscus rosa-sinensis must be hand pollinated, using one bloom as the father (pollen) parent and applying the pollen on to the stigma pads of another bloom chosen as the mother (pod) parent. The mother bloom must stay on the bush for the seedpod to develop. Because of this two-parent system, one never knows for sure just what genes or chromosomes will come through from either parent into the seedling. A developed seedpod may contain one or many seeds."

I had originally tried to purchase hibiscus seeds from some of the large seed companies. In vain - they were not on offer anywhere. However, once I had become a member of the AHS I learned that they keep a seed bank and that as a member I could obtain seeds for free. Soon I happily held the first seeds in my hands. The package contained precise instructions as to how to treat the seeds in order to obtain good germination results. The introduction impressed me:

"These complex hybrids are each unique in individual personality and appearance. Their morphological range goes back a thousand years to surprise you, and may even raise embarrassing suspicions as to the fidelity of their ancestors. None can ever be exactly reproduced - special care in planting and growing is obviously a labour of love."

Several years passed in anticipation and curiosity about the works of art and nature. It was often difficult to keep the seedlings in healthy condition over the winter months. But the big moment arrived: in 2003 gorgeous, multi-coloured blossoms appeared, some of them as large as 17-20cm. I was stunned.

My own efforts to obtain seed through manual pollination were, however, not successful. Seedpods did develop, which proved that the pollination itself was a success, but none of the pods ripened. Sooner or later they were shed. The secret is that temperature and humidity must be constant for 8 to 12 weeks; if these conditions cannot be maintained, even developed seedpods will be shed.

I have grown many plants from seed and it is always a great moment when the first blooms appear. But to obtain a new flower from a seed of Hibiscus x rosa-sinensis means much, much more!

Useful addresses:

USA: American Hibiscus Society, PO Box 12073, St. Petersburg, Florida 3373-2073.
(See also trop-hibiscus.com)

Australia: Australian Hibiscus Society, 5 Wordsworth Street, Strathpine 4500 Australia.

Germany: Deutsche Hibiskus Gesellschaft, Ulla Lengdobler, Oberlindhofstrasse 38, 93173 Wenzenbach, Germany. Email.

France: Hodnik Earl, Le Bourg, 45700 St-Maurice-sur-Fessard, France.

Netherlands: Kuipplanten, Hendric-Jan Gommer, Vossebelt 41a, 7751 SW Dalen, Netherlands

Translated from the German by Ariane Condellis

 

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