Osteospermums, also known as Cape Daisies, are a range of easy-to-grow, flowering garden plants that can be grown in the ground or in containers. They produce abundant, long-petalled, daisy-like flowers in various shades of usually lilac / purplish colours, a succession of which last all through the summer. The button-like centres of the flowers tend to be a the same colour as the petals but in a much darker shade, and the foliage consists of a clump of low-growing, pale green elongated and admittedly, fairly nondescript leaves, but this is attractive enough in its own way. In the perennial Osteospermum, the plant grows outwards along the ground via sprawling stems that get fairly woody with age, and can form a pretty substantial clump that stays green even in winter.
Telling the difference between long-lasting perennial, and short-lived annual Osteospermums is something I've yet to work out, myself. There are frost-tender types of the plant, which are sold cheaply as summer bedding plants (a couple of quid for a pot plant) and treated as annuals in the garden, and last only till the end of summer, being killed by the onset of winter. And, as I've outline above, there is another 'type' of perennial Osteospermum that lasts for years and years, getting bigger over each successive season and soon forming a large, seemingly permanent clump. When you buy Osteospermums as small pot plants from a garden centre however, the plants aren't usually labelled, and as the annual types look near-identical to the perennial varieties (to me, at any rate) I find it's difficult to know what you're buying. It seems this difficulty isn't restricted to me, as when I've asked the nursery-persons at our local garden centre whether any given Osteospermum is a perennial or annual variety, they've seemed pretty much stumped, too.
Of course, one way of finding out which variety of Osteospermum you have is to plant the thing in the garden and see if it survives the first winter frosts, but this isn't exactly ideal. I've noticed that 'fancy' Osteospermums, that have been bred to have flowers in unusual colours of purple, or shades of yellow and buff, tend to be the annual variety. Similarly for the plants with 'pin-wheel' shaped flowers (where each petal is sort of spoon-shaped - thin where it joins the central flower disc and circular at the far edge). In fact the only perennial Osteospermums I've seen are the 'traditional-flowered' variety, which has a mid-purple central disk, with petals that are white with a tint of lilac on the surface, and darker purple below. (Of course you can also buy annual Osteospermums with flowers coloured like this, which complicates the matter).
One reason I'm quite partial to these plants is that they seem to grow well even in very poor soil; we have (in gardening terms) a disaster-area front-garden that was under gravel for about then years, and consists as a result of mostly subsoil with rocks and big lumps of clay mixed in. A perennial Osteospermum has established very well in this area and is thriving, however, and with its abundant woody stems, provides a great deal of material which could be used to propagate the plant via cuttings.
Flowers all Summer longHeat and drought tolerant, these self branching bushy, mound forming plants will attract butterflies and bees to your garden, ideal for garden borders, patio pots and window boxes. Bright lavender, purple and white daisy like flowers are produced all Summer long.