With their big, open faces, long pistils and glorious array of colours, hibiscus are one of the world’s most recognisable fl owers. They ooze tropical breezes and summer holidays, and have long been popular with professional breeders and home gardeners as plants to experiment with in the quest for wonderful new variations.The plants we most associate with this fl ower have their origins in the South Pacifi c, and generally have Hibiscus rosa-sinensis and H. cooperi in their breeding. In the early 20th century, crossbreeding began in earnest in Hawaii, with thousands of hybrids created. The most resilient of these are still cultivated, and remain popular in Australia. This wave of hybridisation added the Hawaiian H. arnottianus to the mix, along with the African coral hibiscus (H. schizopetalus), which introduced distinctive frilly petals and vigour to plants for tropical and subtropical climates.Subsequent breeding focused on increasing fl ower size on compact plants, and hibiscus experienced a revival. These plants with dinner-plate-sized fl owers were introduced as Hawaiian hibiscus, while earlier hybrids became known as Fijian hibiscus. Variable in vigour, some Hawaiian cultivars were very susceptible to pests and disease, particularly under less favourable conditions, which put many people off growing hibiscus. Today, plants grafted on vigorous rootstock are less susceptible to problems.CHOOSING YOUR HIBISCUSHibiscus vary in size, from large shrubs suitable for screening to low-growing shrubs. Vigorous, small-leafed cultivars, such as H. ‘Archeri’ (‘Psyche’) and ‘Andersonii’, are useful fl owering hedge plants. For a pruned standard or small tree, look to ‘Pink Versicolor’ (‘Ruth Wilcox’), ‘Sprinkle Rain’ or ‘White Versicolor’ (‘Swan Lake’). Just remove the lower stems to create a clean trunk and canopy.In recent decades, breeding in France has focused on so-called patio hibiscus: compact plants that branch readily and fl ower profusely. They are useful for pot plants or summer bedding in warm areas, and provide short-term colour in cool-climate gardens during the warmer months, with replacement each year. These hibiscus are marketed in Australia as the Flamenco and Rio Clara ranges, and include the popular ‘Ritzy’ with its fl uoro-orange fl owers. Plants vary in vigour and may not have the longevity of some of the trusted varieties, but they do put on a dramatic show.Some hibiscus are higher maintenance than others. While the Fijian hibiscus have proved to be reliable and low maintenance over the past 100 years, some of the larger-fl owered Hawaiian hibiscus may need more constant care to perform well.
PLANTING & CAREHibiscus are sun worshippers, and flower poorly in shade. In coolerareas, they perform best near a warm north- or east-facing fenceor wall, sheltered from wind. They grow well in coastal gardens but need protection from strong, salty winds.The time to plant is October to December in temperate areas, early spring to early autumn in the subtropics, and after the Wet in the tropics. Good drainage is essential, so choose a spot on a slope, or make a slight mound in clay soils, and avoid low-lying areas where puddles form. A soil pH of 6–6.5 is ideal.The plant’s roots are generally located in the top 30cm of soil, so dig a wide hole to about that depth and incorporate lots of well-rotted manure or compost. Water well after planting, and stake tall plants if they need support. Apply a 5cm layer of organic mulch to help retain soil moisture and encourage biological activity, but keep it away from the trunk.Flowers appear on new growth, potentially from each leaf axil. Hibiscus are responsive to a general garden fertiliser containing trace elements, applied monthly during the growing season.PRUNINGPrune to improve plant shape and encourage more flowers. Somecultivars require little, if any, pruning. It’s best to prune as the shrubsurges into growth. This is in early spring in subtropical and warmtemperate areas (following frosts), and after the Wet in the tropics.Generally, prune hibiscus by no more than one-third, as they canrespond poorly to heavy pruning. To rejuvenate an old shrub, it’s better to prune in stages, reducing its size gradually over a coupleof years. Remove dead or diseased wood, and shape the bush.PROPAGATIONHibiscus are one of the easier shrubs to propagate. In the warmermonths, take semi-hardwood cuttings the length and thickness of a pencil. Remove all but the top two leaves, trim the base just below a node, then plant in a pot filled with coir peat. Put a plasticbag over the pot to maintain humidity around the cutting, place it ina warm, shaded area, and keep moist until new growth is visible.TROUBLESHOOTING Under ideal growing conditions, hibiscus are subject to few pests and diseases. Issues generally relate to cultural practices. In cooler areas, plants may suffer during the first few winters until they become established. Common issues include: Defoliation This may be an indication that the plant is in shock because it’s too cold or too wet.Yellowish leaves Generally a sign of poor nutrition, but this can occur in alkaline or salt-ridden soils, and in winter in cooler areas.
