Mussaendas, often known as Bangkok Roses, are popular throughout the tropics and subtropics of the world. Over the warmer, wetter months of the year they grow strongly and provide quite a show in gardens, particularly in northern Australia. You can spot them at a distance, the shrubs being covered with showy white or pink flowers which at times obscure the leaves. While many of the showy hybrid plants dislike cool dry weather, many of the Mussaenda species are a lot hardier and grow in cooler subtropical districts (such as Sydney) in sheltered spots.
All is not what it seems with a Mussaenda flower. Take a look at a ‘flower’ and what will first strike you are the large showy ‘petals’ which are in fact enlarged floral sepals. These surround the yellow, cream or white flowers. The starry true flowers are 5 petaled and have a crepe like texture. In the species, generally only one of these large floral sepals is produced per flower, however in some hybrid Musseandas there can be as many as 5 large showy sepals per flower.
Mussaendas belong to the Rubiacea family which also includes the Gardenia, Ixora, Pentas and coffee plants (Coffea arabica).
Depending on the species or cultivar, Mussaendas generally grow 1.5 to 2.5 metres (5 to 8 feet) tall in cultivation. They benefit from a light annual pruning – generally undertaken just before the start of the growing season as the weather starts to warm and the soil is moist. In the wild, many species grow as rambling climbers and can grow up trees to heights of 10 metres (30 feet).
Plants are generally in flower from November to May in Australia and throughout the southern hemisphere (May to November in the northern hemisphere) although many of the species can flower almost all year round in ideal climates.
There are over 200 species of Mussaenda which have a very broad distribution from West Africa, through the Indian sub-continent, Asia and down through New Guinea to the western Pacific. One species is native to the Far North Queensland and the Torres Islands. Some 5 species are widely grown in warmer Australian Gardens. Pseudomussaenda, a related genus, once included in Mussaenda, also contains one popular species.
Mussaenda erythrophylla (Ashanti Blood, Red Flag) is native Angola, Burundi, Cabinda, Cameroon, Ivory Coast, Gabon, Ghana, Guinea, Kenya, Liberia, Nigeria, Central African Republic, Sierra Leone, Sudan, Tanganyka, Togo, Uganda and Zaire. This is a sprawling shrub with brilliant red sepals and white flowers with red centres. In the wild it can often climb up surrounding trees. In the garden it can be used as a sprawling shrub, 1 to 1.5 metres (3 to 4.5 feet) high by 2 to 3 metres (6 to 9 feet) wide, or be trained as a climber up a support or an open foliaged tree.
Mussaenda frondosa (Dhobi Tree) is native to India, Nepal, Sri Lanka, Cambodia, Vietnam, Malaysia and, Indonesia. It has white sepals and reddish- orange flowers. It is a smaller shrub 1.5 to 2 metres (5 to 6 feet) tall by 1.5 to 2 metres (5 to 6 feet) wide. The foliage is a lighter green than many other species.
Mussaenda incana (Dwarf Mussaenda) is native to India and Malaysia. It has bright yellow flowers and creamy yellow sepals. This is a low growing shrub 300 to 750 mm (1 to 2.5 feet) tall by 1 to 2 metres (3 to 6 feet wide). It looks great if mass planted as a grouncover and deserves to be more widely grown.
Mussaenda philippica (Tropical Dogwood) is native to the Philippines, Indonesia and New Guinea. The flowers have white sepals and orangy-yellow flowers. It grows 3 to 5 metres (9 to 15 feet) tall in the wild, but in cultivation is more commonly seen as a shrub 1.8 to 2.5 metres (6 to 7 feet) high by 1.2 to 1.8 metres (4 to 6 feet) wide. This species is less widely seen than its well known cultivar Mussaenda philippica ‘Dona Aurora’ (Dona Aurora, Buddha’s Lamp). This was a chance sport first collected in 1915 by Calixto Mabesa on Mt Makiling and then recollected by Hugh Curran and Mamerto Sulit at the College of Forestry grounds at the University of the Philippines Los Banos in 1930. This cultivar has multiple floral sepals (often 5 per flower) instead of just one. This was propagated and dedicated in 1930 to Mrs Aurora Quezon, wife of the Philippines President. This plant is the parent of almost all hybrids.
Pseudomussaenda flava (prev. Mussaenda luteola, Mussaenda glabra), (Dwarf Yellow Mussaenda) is native to Ethiopia, Sudan, Kenya, Uganda, Nigeria. This shrub has white floral sepals and creamy yellow flowers. While no longer in genus Mussaenda, it shares many traits and is the hardiest species, tolerating more dryness and cooler temperatures. You will see it growing vigorously as far south as Sydney. This plant blooms all year round in the tropics and subtropics. The flowers also produce a faint perfume.
Hybrid Mussaendas are probably those most popularly grown in warm climate gardens. Hybridisation started in the mid 1940s at the University of the Philippines at Los Banos. Much of this work was undertaken by Dr Dioscoro Umali, Dean of the College of Agriculture, and his wife using ‘Dona Aurora’ crossed with Mussaenda erythrophylla. ‘Dona Aurora’ does not set viable seed but produces viable pollen. Many of the popular shrubs growing in Australia date from the early days of this hybridisation. Work at the University on the genus has continued to this day, however you will have to travel to Asia to see some of the more recent cultivars.
Mussaenda ‘Queen Sirikit’ (Mussaenda ‘Dona Hilaria x Dona Aurora’) is named for Queen Consort of Thailand, the longest reigning head of state in the world. It is possibly the most widely grown Mussaenda in the world. It has multiple pale pink sepals which have a distinct darker edge. Flowers are bright yellow. Following heavy rain, the weight of the flower heads has been known to break branches.
Mussaenda ‘Dona Luz’ (M. ‘Dona Hilaria x Dona Aurora’) is named after Philippines First lady Luz Banzon-Magsaysay. It has multiple shrimp pink sepals which are inclined to turn under at their tips.
Mussaenda hybridisation has also occurred in India in recent years. One hybrid from this country is grown widely in Australia and around the world.
Mussaenda ‘Marmalade’ (Mussaenda Dona Luz x P. flava) is a patented shrub raised from seed in 1995 in a nursery in Alipore, India. This shrub is very hardy and vigorous – the result of having P. flava in its breeding. It grows quickly to 2 to 3 metres (7 to 9 feet) high 1.8 to 2 metres (6 to 7 feet). The shrub is covered with showy yellow and salmon deepening to yellow and orange sepals. They are smaller than many other hybrids, but they are very showy on the bush. I highly recommend this plant. It continues to grow in my estimation. In Australia this plant has been rebranded as Mussaenda ‘Calcutta Gold’ by local nurserymen, which once again causes confusion when the public try to get further information from the internet.
A number of Mussaenda Hybrids have also been developed at Osram Nursery in Rockhampton, Queensland. The first two to be released have proved to be hardy and popular both here and overseas. Further plants are to be released in the future following international plant patenting.
Mussaenda ‘Capricorn Dream’ has multiple scarlet red sepals and it makes quite a show in the garden.
Mussaenda ‘Capricorn Ice’ – has multiple white sepals and deep yellow flowers.
Mussaendas perform best in humid tropical and subtropical areas, although many species and some hybrids will do well in protected areas in warm temperate areas as far south as Sydney. Plants like sheltered locations in full sun to semi-shade, and a northerly to eastern exposure (southerly in the northern hemisphere).
Plants thrive in organically enriched fertile soils that have been heavily mulched and where they are regularly fertilised. Like many other plants in the family Rubiaceae, they can be subject to nutrient deficiencies, particularly trace elements. This is all too common in high rainfall areas where nutrients are readily stripped from the soil. I like to use biological fertiliser which includes balanced ground rock minerals. These are more likely to be retained in the soil and released over a longer period. Plants also benefit from regular organic, foliar fertiliser applications. Dilute the liquid fertiliser to ½ the recommended rate and apply early in the morning or in the cool of the evening. Irrigate plants during dry periods as Mussaendas suffer from dryness and can defoliate and die back.
While evergreen in the tropics, plants can defoliate and die back in cooler or less sheltered locations over late winter and early spring. It is best to best to prune them just as the weather starts to warm and before the shrubs shoot into growth This is around mid-August to early September (February to early March in the northern hemisphere). As plants increase in size and become more established, they tend to defoliate less frequently. Many people appreciate the plants’ performance during the warmer months of the year and are prepared to tolerate ‘sticks’ during the winter months. In cooler climates, plants can be grown in pots and moved to a greenhouse or veranda during the cooler months.
Pseudomussaenda flava, Mussaenda erythrophylla, Mussaenda frondosa and Mussaenda incana are the hardiest species in that order and Mussaenda ‘Marmalade’ is the hardiest of the hybrids. Mussaenda ‘Capricorn Ice’ and Mussaenda‘Capricorn Dream’ are also said to be hardy, and I have seen them both flowering in sheltered Sydney gardens, but being recent introductions, time will tell.
Mussaendas tend to be rambling shrubs and benefit from an annual pruning. Generally it pays to remove no more than 1/3 of the growth. If serious renovation is required, it is better to do a series of pruning sessions over a longer period, gradually reducing the size as necessary. Certain species and cultivars can also be trained as climbers, up arbors or along fences. Plants also benefit from removal of dead flowers and bracts throughout the flowering season.
Propagation of these plants is from cuttings taken during the warmest months of the year. Some species and hybrids are harder than others and in the home garden they can also be readily propagated by layering. Overseas, tender hybrids are often grown on Pseudomussaenda flava as a rootstock with great success.
Mussaendas are generally planted at the rear of garden borders. Being taller plants, their bases are often bare and benefit from a border of lower shrubs or groundcovers. Take care to select plants that are not to vigorous and may compete with these plants.
In flower, Mussaendas can be showy, if not spectacular visible when seen from a distance. The hybrids are often covered in showy sepals to the point that the leaves are barely visible. The majority of the hybrids that have sepals that are white and shades of pink and can work well with plantings with complement pastel tones – both flowers or foliage. However a few species and cultivars have brilliant red and yellowish-orange sepals and these plants can be combined well with hot borders and brilliant foliage to create sizzling plant combinations. Mussaendas scream “tropical”, but I have seen them used in cottage gardens with “flowery” perennials.
Mussaendas are generally pest free, particularly if their nutritional and climatic needs are met. They can be subject to scale, mealy bug. In turn this can lead to sooty mould growing on honey dew. This seems to be worse when plants grown up against a house where the warm, dry conditions encourage these pests.
Have a think about where one of these plants might do well in the garden and earmark that spot …… a warm sheltered northern location where it will get sun for much of the day. Better still, how about a mass planting of your favourite cultivar or species? There is nothing like making a strong statement in the garden! These shrubs are sure to give you pleasure over the warmer months of the year and for many years if not decades into the future.