Three plants that look good together: Solanum jasminoides `Album' Clematis armandii Agapanthus `Snow Owl'
This week's "three" require sheltered, cosseted spots, warmed by as much sun as possible. Such positions are prime sites in any garden, providing a chance to indulge in exotic species. But while the competition is fierce for such space, plant these three together and from April to September they will give you a succession of abundant white blossom and heady scent.

The Potato vine, Solanum jasminoides "Album", is the most tender. It comes from upland areas of Brazil and has some familiar cousins - the potato, the aubergine and the poisonous Deadly Nightshade. Many people will have gardens too cold and exposed to try it (although it does grow as far north as Edinburgh) and will have to grow it in a cool greenhouse or conservatory.

It is a sprawling, twirling, clambering thing, with rampant woody branches, which will reach about 18ft against a wall. Its narrow, dark green, glossy leaves, a couple of inches long, are semi-evergreen in mild winters. Individually, its crisp, star-like flowers are small, but cluster together in heads of about 10 blooms. Each has five, fleshy white petals around a centre of bright yellow anthers, which come to a point rather like a beak. They begin to open and release their perfume in late spring and can continue unchecked until the first frosts.

Clematis armandii, is better known than the Potato vine and less tender. Even so, it needs a sheltered site, for it is not completely hardy and frosts can cause ugly damage to its leaves and flowers. Like the Potato vine it is a vigorous climber and has abundant, scented, white flowers, but they are saucer-shaped, larger and appear in spring.

The clematis is as well known for its leaves as its blossom. They are large and evergreen, smooth and dark, glossy green and, when young, a light copper colour.

If there is room at the feet of these climbers, the African lily, Agapanthus "Snow Owl", makes a fine companion. It is hardy in sunny, well-drained spots, but will benefit from a protective winter mulch in cold areas.

It is a long-lived perennial with broad, strap-shaped leaves and flower heads like small footballs, made up of white, lily-like flowers. These striking clusters are held above the foliage on long, smooth leafless stems in late summer. Don't be hasty to cut down these stems as the globes of flowers fade, for they become attractive seedheads in the winter garden.