Honey Bush, Melianthus major, in Ventnor Botanic Garden.

It is just over a year since we replaced the raised bed in our front garden and the plants have already bulked up and settled in. The Honey Bush, Melianthus major, in the centre of the bed, is looking particularly lush and put on a big growth spurt in the early autumn.

I first encountered Melianthus major at the Priory Maze Gardens at Beeston Regis, near Sheringham in North Norfolk, a few years ago. I was struck by its spectacular glaucous foliage and, brushing against its leaves, its scent of peanut butter. After that I started to notice it growing elsewhere, such as a front garden I often walk past on Earlham Road in Norwich and in the lovely Ventnor Botanic Garden on the Isle of Wight. Here, in a mild climate and a very sunny spot, the plants were flowering and setting seed.

Melianthus major is a native of South Africa, although it has been introduced into India, Australia and New Zealand. It can grow to 2 to 3 metres (7 – 10 feet) tall within the space of one season and plants can be at least as wide as they are tall. Melianthus major has pinnate, blue-green leaves with serrated edges, each of which can grow over a foot (30 centimetres) long. It is a member of the family Melianthaceae.

Melianthus major can stand a slight frost (hardiness H3), down to about -4 degrees Celsius, and on days when the temperature dips just below freezing point, our plant droops, but then recovers. In colder weather, the stems can die back completely, but the roots are pretty hardy and the plant will grow back in the following year. In South Africa Melianthus plants sometimes die back during summer droughts but the autumn rains encourage the rootstock to regrow and the plants put on lush growth in the winter rainy season. Gardeners often cut back their Melianthus major plants to keep the plant smaller and neat. This is best done in spring, as the old foliage protects the plant from frosts.

In a warm, sheltered spot where the foliage hasn’t been cut back, Melianthus major will produce racemes of flowers in spring. These are 30 – 80 centimetres (12 – 31 inches) long. The flowers are almost the colour of dried blood – described as dark maroon, brownish crimson to brick red or dark red. They are full of nectar. In South Africa they are visited by bees and by nectar-feeding birds, such as sunbirds, white-eyes and red-winged starlings.  The flowers are followed by green seedpods. Linda Cochran grows Melianthus major in Port Ludlow, Washington, in the United States and her blog has some good photographs of the flowers and seedpods. The Plants Africa website has more detailed photographs of the flowers and describes their structure.

Melianthus produces large amounts of black nectar, which can literally drip from the flowers (and stain clothing). The scientific name Melianthus major means “large honey flower” and, as well as ‘Honey Bush’, English names for the plant include ‘Honey Flower‘, ‘giant honey flower’ and ‘touch-me-not’.

I like to squeeze Melianthus leaves for the peanut butter aroma, but not everyone likes the smell. The name ‘touch-me-not’ comes from the smell of the leaves and is a translation of the Afrikaans common name for the plant, kruidjie-roer-my-nie, which means ‘touch-me-not-herb’. Perhaps the smell is stronger in a hot climate?

Although Melianthus major smells of peanut butter, don’t be tempted to nibble the leaves, for the plant is poisonous. According the Plants For A Future website, the root is the most poisonous part of the plant. The nectar is very sweet and is sometimes eaten. Thomas C. Fuller and Elizabeth McClintock write in “Poisonous Plants of California” that honey from Melianthus flowers “is considered toxic” but Plants Africa says the plant “is said to produce good honey“.

In South Africa, Melianthus is used in traditional medicine. According to Plants Africa: “The leaves are used to make poultices and decoctions to treat septic wounds, sores, ulcers, boils, abscesses, bruises, backache, painful feet and rheumatic joints. The roots and leaves are used to treat snakebite, or taken in very small doses as a tonic. It is also used to make a gargle for sore throats and mouth infections. Dried flowers and leaves can be used to keep insects out of cupboards”. The plant is usually avoided by livestock because of its smell.

Melianthus major contains bufadienolides, (named after the toad, Bufo), cardiac glycosides that increase the output force of the heart and decrease its rate of contractions. (Other poisonous plants that contain cardiac glycosides include the Foxglove, Digitalis purpurea, and the Lily-of-the-Valley, Convallaria majalis.)

But don’t let the fact that it is poisonous stop you growing this magnificent plant.

Melianthus major likes a sheltered sunny spot and reasonably well drained soil. Once established, it copes well with drought, though my plant wilted very quickly in the couple of months when it was in a pot, prior to being planted in the raised bed.

If you want to produce more plants, Melianthus major is easy to raise from cuttings taken in spring and grown in a greenhouse, or from seed. The plant appears to have few pests, though whitefly and red spider mites could be a problem in a greenhouse and Cool Tropical Plants mentions that older leaves can be attacked by aphids.

Melianthus comosus is a more compact relative, whose leaves have attractive copper-gold undersides. It also comes from South Africa and is said to be very suited to British gardens.