Fancy foliage
While some plectranthus species are weedy in New Zealand, the better behaved members of the family can make a wonderful addition to gardens.
Pretty well-behaved plectranthus.
Commonly known as spurflowers, plectranthus are a diverse group of plants, with many ornamental species in the genus.
Mention plectranthus to many gardeners, particularly those who reside in the northern end of the country, and their eyes will widen in horror. They’ll probably be thinking of the weedy Plectranthus ciliatus or one of its relations, all suffering an ignominious reputation due to their ability to spread rapidly by stem fragments in shady or moist areas. But there’s much more to this genus than these few errant species. Commonly known as spurflowers, plectranthus are a diverse group of plants, with many ornamental species in the genus, including shade-loving shrubs, drought tolerant succulents, evergreen perennials, groundcovers and pot plants. Several have both striking flowers and attractive foliage. This, combined with an easy care nature, fast growth rate, ability to grow in shade and ease of propagation from cuttings have made them popular with gardeners around the world.
While the latter attributes might have contributed to the invasive reputation of some species here, recent cultivars and hybrids do not spread as easily and are considered very good garden subjects. At this stage, only a few are available in New Zealand but as their popularity continues overseas, hopefully this will change.
Plectranthus are southern hemisphere plants from the Lamiaceae or mint family, with roughly 350 species native to India, sub-Saharan Africa, Madagascar, the Indonesian archipelago, Australia and some Pacific islands. Plectranthus parviflorus is said to be native to New Zealand, Australia, Hawaii and parts of Polynesia. The plant has aromatic leaves and small purple flowers. It prefers moist, open areas or partial shade under shrubs and trees. Plants may still be available at Oratia Native Plant Nursery (oratianatives.co.nz) but get in quick; the nursery closed recently and is selling only its remaining stock.
Kate Jury of Seaflowers, a mail order nursery specialising in rare and unusual plants, grows three forms of plectranthus. She agrees that the genus has a bad rap here. “Gardeners in New Zealand are very well-informed about the weedy nature of some plectranthus species. But information can be very generalised sometimes, and non-weedy species and cultivars are frequently tarred with the same brush as their rampant cousins, which is a shame as some of them make wonderful garden plants.” They’re also incredibly useful plants with numerous species grown for medicinal or culinary purposes. In Saudi Arabia, Plectranthus barbatus (considered a weed by some here) has been used for centuries as a remedy for stomach, intestine and liver disorders as well as heart problems and respiratory diseases. Herb lovers could consider growing Plectranthus amboinicus, a succulent with fleshy leaves that is added to dishes in India, South Africa, the Caribbean and many other tropical countries. It is commonly known as Cuban oregano, Indian borage, Mexican mint and a variety of other names. Now gaining attention among herbalists in the Western world, it’s also been used traditionally in India and other tropical regions including Southeast Asia and South America for centuries to cure a number of ailments including insomnia. Use the herb in teas, stir-fries and casseroles. There are even edible tubers in the family: the Livingstone potato, Plectranthus esculentus from southern Africa and the Ethiopian potato, Plectranthus edulis. One of the earliest plectranthus cultivated in Europe was Plectranthus oertendahlii or Swedish ivy, grown for over 100 years now, mainly as a houseplant (just be cautious growing it outdoors in New Zealand). As its name suggests, this plant was likely collected by an unknown Swedish missionary or surveyor and taken back to Scandinavia. Since then, the attention of gardeners has focused on a few ornamental species, but it was not until the end of the last century that interest began to galvanise, sparked largely
Look further into the Plectranthus genus and you’ll find it contains some incredibly useful plants with numerous species grown for medicinal or culinary purposes.
by publications on plectranthrus, particularly those produced by Ernst Van Jaarsveld, a horticulturist at Kirstenbosch National Botanical Garden (now known as the South African National Biodiversity Institute) in Cape Town.
New and improved
It was Ernst who began a hybridising programme which led to the development of Mona Lavender ( Plectranthus ‘Plepalila’). A cross between Plectranthus hilliardiae ‘Magwa’ and Plectranthus saccatus, Mona Lavender was released in 2002 by Roger Jacques, another Kirstenbosch horticulturist.
An evergreen shrub, it grows to around 75cm in height and 60cm wide, ideal for hedges and borders. It also does well in containers and hanging baskets if kept trimmed. Beautiful mauve flowers are produced from late summer to autumn while interest is maintained throughout the year by its lovely glossy foliage with wine-coloured purple undersides.
A more recent release is Plectranthus saccatus ‘Velvet Elvis’ from plant breeders Terranova Nurseries in the US. The company says the flowers of ‘Velvet Elvis’ are larger and a deeper lavender than Mona Lavender, its textured leaves a very deep green and its habit more compact. With a long flowering period like Mona Lavender from late summer to autumn, this shrubby perennial is fast-growing, and suitable for gardens and containers. Both Mona Lavender and ‘Velvet Elvis’ are available at selected nurseries here as well as Bunnings.
South African plant breeder Gert Brits used the same cross of species as Mona Lavender to develop the frost-resistant Cape Angels series followed by the Jazz It Up series for use as container and garden plants. Unfortunately, the hybrids are not sold in New Zealand.
Locally grown
One of the few commercial growers of plectranthus in New Zealand, Kate Jury’s Seaflowers Nursery produces two Plectranthus fruticosus cultivars ‘Behr’s Pride’ and ‘James’ as well as Mona Lavender.
Kate says ‘Behr’s Pride’ has amazing foliage – a dark green above, with the leaf undersides and the stems about the colour of blackcurrant juice. “I grow mine on a low bank at eye level, where I can admire the stems and leaves as it grows skywards, but it also appeals in autumn when the dense spikes of bright pink flowers appear,” she adds.
“‘James’ is a good choice for smaller gardens, rarely growing more than a metre. It’s got lovely thick, crinkly leaves and spikes of pink flowers.
“Mona Lavender is very similar to the recently released ‘Velvet Elvis’. I haven’t grown the latter yet, but from pictures I can see they are both beautiful, with Mona Lavender having slightly smaller flowers. I love her both in the garden and in large pots, as she flowers for a long period and the dark purple, almost black, leaf undersides are gorgeous.”
An evergreen shrub, it grows to around 75cm in height and 60cm wide, ideal for hedges and borders.
Well-travelled varieties
From across the Tasman comes Plectranthus argentatus, commonly known as silver spurflower. Native to the border region of Queensland and New South Wales, it has velvettextured silvery-green leaves and bluish-white flowers in summer.
More of a woody perennial or subshrub, the plant can be upright or sprawling. Evergreen in warmer areas, it is often grown as an annual in colder places. It will grow up to a metre in height, spreading to 3m.
The cultivar ‘Silver Shield’ is more compact than the species and there is a variegated form as well: ‘Hill House’ is bred by Hill House Nursery in Devon, in the UK.
Hard to find
While the silver spurflowers are here, they are not easy to come across in New Zealand. Neither the species nor cultivars are sold commercially here, as Margaret Barker, owner of Larnach Castle in Dunedin, and a regular NZ Gardener columnist, discovered recently when she wrote of losing her plant one winter and being unable to replace it.
Fortunately, fellow gardeners and readers were able to help out. “Although plectranthus are not generally hardy in Dunedin, and only survive in a carefully chosen position, the Plectranthus argentatus that readers of NZ Gardener kindly sent me have come through this winter in the garden,” she reports.
Interestingly, NZ Gardener editor Jo McCarroll gave Margaret some ‘Velvet Elvis’ plants which have also – surprisingly – survived the colder temperatures, Margaret says.
“They have been used within the castle in the plant displays on the conservatory area and look very attractive. They have flowered inside. I planted one outside in the rainforest garden behind the ballroom to test its hardiness and it came through the winter looking just great.”
Similarly, Plectranthus amboinicus is not commonly available in New Zealand but there’s no need to despair – some specialist herbal growers such as the Canterbury Herbal Society and a few online retailers list it in their catalogues.
Another plectranthus species not commercially grown but still found in many gardens is the succulent commonly known as Vicks plant or dogbane, Plectranthus neochilus (syn. Plectranthus caninus). Kate Jury describes it as “stunning when in full flower in a sunny spot, but it really does pong, so is best planted away from paths and people.”
You can usually find Plectranthus neochilus and the other hangingbasket types as cuttings given away by generous gardeners or they are sold on Trade Me, she says.