Small Hibiscus and Hibiscus-like Plants in Pots

Colleen Keena

Introduction

Although new species of hibiscus and hibiscus-like plants are still being found and recorded, the beauty of at least one species was recognised as long ago as 1828. The Colonial Botanist of New South Wales, Charles Fraser described Hibiscus splendens as the King of all the Australian plants he had seen. He described the flowers as being the most delicate pink and crimson and literally covering the plant. Hibiscus splendens is just one member of the Hibiscus family. Australian representatives vary in size from a ground cover, Abelmoschus moschatus, to small plants such as Hibiscus trionum and H.geranioides (0.5m), to medium shrubs such as Alyogyne huegelii (1-2.5m) and tall trees such as Lagunaria patersonii (to 13m). Not only is there a range of sizes but members of this family can be found growing in tropical areas (Abelmoschus manihot), in swamps and crater lakes (Hibiscus diversifolius), along the beach (H.tiliaceus), in inland Australia (Gossypium sturtianum, Alyogyne hakeifolia), in fissures in sandstone in open forest or along rainforest margins (H.splendens) and along the margins of light rain forests on soils ranging from loam to granitic or poor and gravely (H.heterophyllus).

While most species occur in subtropical and tropical regions, some species can be grown in temperate climates, e.g. Hibiscus splendens and H.diversifolius if kept well watered. Other species can be grown in warm temperate zones, e.g. Alyogyne hakeifolia, A.huegelii, Hibiscus heterophyllus and H.tiliaceus. Hibiscus plants grow even under tough conditions, e.g. remnant stands of Hibiscus heterophyllus growing on hillsides near Brisbane showed no adverse effects from the recent prolonged drought and in the Wide Bay district, roadside plants of H.divaricatus re-grew after being burnt. One species, Alyogyne huegelii, has been described as thriving in the most desolate of places.

"This prolonged flowering and the production of nectar contributes to the value that Hibiscus species have for "faunascaping""

Depending on the species, flowers may be white, various shades of yellow, pink, purple, or red. Flowering times vary according to the species but in a subtropical climate such as Brisbane, by planting a range of species, it is possible to have plants flowering throughout the year. This prolonged flowering and the production of nectar contributes to the value that Hibiscus species have for "faunascaping". Not only will blooms which produce nectar feed nectar-eating birds and predators but they will also attract insects for insect-eaters, provided there are protected water sources and nesting places for birds. In addition, the seed capsules of species such as H.heterophyllus can provide for seed-eaters. Thus, apart from any aesthetic appeal of birds and insects, plants such as hibiscus species which attract birds and predators encourage natural pest control as the insects use the plant as a food source and are themselves controlled by a wide range of predators. Honeyeaters take advantage of the large nectar-rich flowers of species such as Alyogyne huegelii, Hibiscus diversifolius, H.heterophyllus and H.splendens. Birds such as lorikeets are attracted to species like H.heterophyllus and the sight and sound of a H.heterophyllus literally covered with lorikeets bowing down the branches as they feast upon the seed capsules more than compensates for any damage sustained. Insects seek out the flowers of H.diversifolius, H.heterophyllus, H.splendens and H.tiliaceus, and H.tiliaceus is a butterfly food source. It could then be argued that any list of plants suitable for pots would be incomplete without representatives of the Malvaceae family.

Species Suitable for Pot Culture

The first plants which will be described as suitable for pot culture are lemon or yellow. Hibiscus panduriformis can be either a shrub or prostrate plant. Seed of the procumbent form was obtained from Western Australia and the plants have performed well in pots. The flower is bright yellow and the first buds appear at the end of winter. H.trionum is an annual, flowering in the warmer months and growing well in pots. A form called "Sunnyday" is recommended as the flowers are longer lasting and brighter yellow than the flowers of the species which occurs on the outskirts of Brisbane. H.diversifolius also occurs in south east Queensland and northern New South Wales. Plants observed growing in swamps were close to two metres in height but cuttings of these flowered at less than one metre when grown in pots.

Of the pink flowering small hibiscus, Hibiscus geranioides is probably the most readily available, although it may be an introduced species. It has pink tubular flowers throughout the warmer months. There is a form of Hibiscus diversifolius with maroon-purple flowers. This form which is around one metre flowers throughout the year and grows well in a pot. Another pink hibiscus which grows well in a pot is Pavonia hastata . This may also be an introduced species. Plants are cut back at the end of winter and flower prolifically from December to May. Seedlings do come up in nearby cultivated beds but none have ever grown in the bush section of our block.

Pavonia hastata is a small shrub to about 1 metre. The pale pink flowers with a deep red throat are seen in summer and autumn. Select the thumbnail image or plant name for a higher resolution image (26k).

Even the larger hibiscus such as Hibiscus heterophyllus, H.splendens and H.divaricatus and hybrids between these species can be grown in pots. If a seedling is grown, not only might the flowers be a long time coming, but it will be difficult to maintain the plant in a pot. If cuttings are taken, instead of the tap root system of a seedling, the plant has fibrous roots and is then much more amenable to being contained in a pot, particularly if the plant is tip-pruned from the earliest stages. The result is a bushy plant that flowers freely and much earlier than it would as a seedling. The cutting-grown plant usually flowers within approximately six months, often while still in 9cm pots.

While not from the Australian mainland, and not small, Hibiscus insularis (Philip Island Hibiscus) must be mentioned. Again, cutting-grown plants as opposed to seedlings, perform well in pots, flowering freely while small. The delicate flowers are initially lemon but turn mauve as they age. Pruning is important for all large species and regular tip-pruning is preferred as plants that have to be cut back to wood may not survive. The size of the pot governs the size of the plants and so size can be easily restricted by limiting pot size - give them a big container and they will become very large. I can manage these species indefinitely in shade house conditions in 9cm pots. However, as soon as the larger species of hibiscus are planted into even 15cm pots they start to shoot up and out and constant tip-pruning is necessary. Plants can be potted on until the desired size is reached and then maintained at that size by pruning. My stock plants have been allowed to reach 1.5-2m as this size provides plenty of cutting material. The largest size of pot that I use is 40cm.

Other members of the Malvaceae family are ideal for pot culture. Abelmoschus moschatus "Mischief" performs extremely well in a pot. This form bears bright red flowers with white centres throughout the warmer months, particularly at Christmas. A. manihot grows from 1 to 4 metres, however in a pot it can be kept around the 1 metre size. It has large lemon flowers in autumn and is probably best treated as an annual/biennial.

Abutilon deserves to be more widely grown. So far I have only grown Abutilon auretum and A. sp.Chillagoe . A.auretum is showy with almost continuous buttercup yellow flowers and attractive seed pods. A. sp. Chillagoe is more subtle in colouring. Both perform well in pots. A. sp. Walshs Pyramid has 10cm white flowers with maroon centres and grows to around 1.5m but cutting-grown plants in pots flower when very small.

Alyogyne huegelii is a popular landscaping species for dry areas. The flowers are usually mauve to purple but may also be seen in white or yellow. Select the thumbnail image or plant name for a higher resolution image (19k).

Alyogyne huegelii and A.hakeifolia have been grown from seed and have flowered while still in pots. Both these species are available in shades of mauve or in white. Alyogyne huegelii has been successfully grafted onto plants of a small growing Hibiscus heterophyllus x splendens hybrid as I have previously lost A.huegelii in humid conditions. Alyogyne huegelii grows larger than 1 metre but cutting grown plants flower profusely in pots while well under a metre and these plants also appear to be superior to plants grown as seedlings. These flowers last for several days whereas all other local species mentioned only last for one day. Gossypium australe , G.sturtianum and G.robinsonii, with mauve flowers, have also been grown from seed and have flowered in pots from seedlings. They may perform even better if grown from cuttings or grafted.

All plants mentioned have grown well in pots in south east Queensland. This is only some indication of Malvaceae suitable for pots. There is still much to be learnt and many plants are still elusive, either because they are difficult to obtain e.g. Hibiscus sturtii or because they succumb during our wet summers, e.g. Hibiscus farragei (syn.Radyera farragei).

Challenges Associated with Hibiscus

Although hibiscus can enhance the garden, they are not without problems. Susceptibility to frosts has to be considered, although most are hardy plants in areas where only light frosts are experienced. Species such as Gossypium australe and G.sturtianum are frost resistant while species such as Hibiscus heterophyllus and H.splendens will need extra protection in frost-prone areas but do grow well in frost prone areas against a wall or fence. It appears to be possible to overcome susceptibility by careful selection of hybrids, for example several of a number of hybrids between H.heterophyllus and H.splendens have recently survived -6 degrees even though the naturally occurring species growing on the same site were either damaged or destroyed. Another difficulty is that in some species such as Hibiscus diversifolius, H.heterophyllus and H.splendens and Abelmoschus manihot, the seed pod is covered in hairs that may cause severe skin irritation. Sticky tape stuck onto the skin and then pulled off appears to be the easiest and most effective way to remove these irritant hairs as well as using tweezers when extracting seed.

"Then there are a variety of sucking or chewing creatures that enjoy the flavour of both buds and leaves, although......control is usually not warranted...."

Then there are a variety of sucking or chewing creatures that enjoy the flavour of both buds and leaves, although well grown plants are less likely to be attacked by either pests or diseases and control is usually not warranted, especially if it is appreciated that many pests represent an important food for birds and predators and if the garden already has birds and other predators present to clean up most pests. Hibiscus beetles mostly feed on the pollen of the hibiscus flower and may chew holes in the petals but there is no need to kill them. Even though Harlequin bugs depend on the sap they suck from species such as hibiscus, the damage done is rarely serious and their colours are so spectacular that they can even be considered desirable. Scale insects can become a problem but can be easily managed either by removing by hand or even by cutting off affected parts. Any other damage that may occur can also be pruned off. Regrowth is so fast after pruning the plant may actually be improved. Pruning to maintain a desired size or shape may be seen as a chore, however the plant repays the effort as the result is a more compact plant with a much greater number of flowers.

Probably the major obstacle to incorporating Hibiscus and Hibiscus-like plants is availability of plants. Few nurseries regularly carry Australian species. Currently, seed of some species can be obtained either through the various SGAP seed banks (members only) or through commercial suppliers of wildflower seeds. Although it is over 150 years since Charles Fraser described their beauty and despite their adaptability and ready flowering, this same plant and many of its close relations are not yet readily available in nurseries or if available may be incorrectly or inadequately identified. The difficulty with obtaining plants is likely to continue until the potential of this long ignored family of plants finally begins to be recognised.

References

Australian Plants Study Group, 1980-85; Grow What Series, Thomas Nelson, Melbourne.
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Beers, L. And Howie, J., 1985; Growing Hibiscus, Kangaroo Press, NSW.
Bodkin, F., 1986; Encyclopaedia Botanica, Angus and Robertson, Australia.
Craven, L.A. and Fryxell, P.A., 1993: Additions to Australian Hibiscus (Malvaceae): A New Species and a New Record. The Beagle, Records of the Northern Territory Museum of Arts and Sciences 10(1):1-6
Clyne, D., 1984; More Wildlife in the Suburbs, Angus and Robertson, Australia, p.181-184.
French, J. The Wilderness Garden, Aird Books, Melbourne.
Hacker, B, Butler, R. And Rekdahl, R., 1994; Putting Back the Forest, Rural Environment Planning Association Inc, QUT Printing, Australia.
Hadlington, P. And Taylor, T., 1992: The Native Garden Doctor, Simon and Schuster, Sydney.
Holliday, I. And Lothian, N., 1964,1974; Growing Australian Plants, Rigby, Australia.
Hutchison, F., 1990; Creating a Native Garden for Birds, Simon and Schuster, Sydney.
Mason, J., 1989; The Native Plant Expert, Australian Horticultural Correspondence School, Victoria.
McMaugh, J., 1968; What Garden Pest or Disease is That?, Companion Edition, Lansdowne, Sydney.
Molyneux, B. And Forester, S., 1988; The Austraflora Book of Australian Plants, Penguin, Melbourne.
Simpson, A.G.W., 1982; Bush Garden Handbook, Rigby Publishers, Australia.
Wrigley, J. And Fagg, M., 1996 Australian Native Plants, Fourth Edition, Collins, Sydney.

Reprinted from the March 1997 newsletter of SGAP's Australian Plants for Containers Study Group.

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Australian Plants online - September 1997
The Society for Growing Australian Plants