It’s time to pull out pansies and violas and other winter flowering annuals and replace them with something that will put on a show through summer. One of my favourite warm season annuals is Vinca.
This tough little thing looks very much like a New Guinea Impatiens, with smallish, glossy green oval-shaped leaves and masses of simple, flat flowers each consisting of five petals arranged around the centre. The colour palette is also similar, mostly whites, pinks, mauves, purples and reds. But where Impatiens love to grow in a moist, fairly shaded spot, Vincas like to be out the blazing sun, and prefer to be a kept a bit dry.
But the plant we commonly know as Vinca has actually had a name change fairly recently, and is now classified as Catharanthus roseus. It used to be called Vinca rosea, and the ’Vinca’ tag has stuck. Like many plants, it has a host of common names, including Bright Eyes, Cape Periwinkle, Madagascar Periwinkle, and Graveyard Plant (because it is a tough, low water-use plant that is sometimes planted in cemeteries). It is native to Madagascar, where it is endangered in the wild thanks to habitat destruction caused by slash and burn agriculture.
It is widely cultivated, however, both in gardens and in commercial horticulture. The plant, long used in traditional medicine in Africa and Asia, contains powerful alkaloids which are used in certain chemotherapy drugs. But like many plants which produce white sap, Vinca is poisonous and so must not be eaten.
The ornamental cultivars we grow in our gardens are usually treated as annuals, although they may last several seasons if the weather stays warm. There are low, spreading forms with a trailing habit, great for hanging baskets, tall pots, or as a colourful groundcover. There are also taller, more upright forms. All flower profusely from a young age.
One of the many things I love about them is that they are self-cleaning. When the flowers finish, they just drop off cleanly and you don’t have to deadhead the plant to keep it looking neat. They may set seed, which germinates readily in warm weather, so you might find some popping up the following year.
Although they are tough and drought-hardy, Vincas will still look better if you give them a bit of attention. Improve the soil before planting or use a premium potting mix if you are growing them in a pot. They do need a sunny position, and very good drainage. They will not thrive in heavy, waterlogged soil. A liquid feed every now and then will keep the flowers coming.
The taller varieties might get a bit leggy, but if this happens you can prune them and they will probably come back bushier than ever.
Vincas are usually sold in seedling punnets or as potted colour. Either way, they are a wonderful, inexpensive way to get a lovely summer show that will look great despite the heat and with minimal water.