Plectranthus hail from warm temperate to tropical areas of the world (particularly South Africa) and grow in shadier parts of the garden under trees in very ordinary soil where many plants do not thrive. They grow quickly and are tolerant of drought and root-competition.
South African Plectranthus saccatus (ht 1m) is a low-growing shrub with jacaranda-blue, pouched blooms, which are larger than most other Plectranthus. It has pretty, scalloped-edged leaves. It is an almost indestructible plant in the most inhospitable conditions of dry shade where it will form ribbons of colour as its cane-like stems scramble through other plants, or even climb up fences. It can be grown almost as a shrubby groundcover - or else clipped to a rounded shape. It is an excellent companion to the jewel-like flowers of pink, white or purple Impatiens, adding just the hue that they lack. It grows well with cane and shrub Begonia plants, which also flower well in shade. It looks very effective grown with gold- or lime-coloured leaves, such as golden Duranta or with greenish-yellow flowers, such as those of Justicia brandegeeana or Nicotiana langsdorffii. In South Africa, there are a number of named cultivars, including a white one and types with speckling and stripes on the flowers.
It can begin to flower in summer but seems at its best in autumn. It can be grown in a pot. Prune back after flowering, or in early spring in colder areas. It is frost sensitive, but if grown in the shade of taller shrubs and trees, this will provide some protection. All Plectranthus need to be replaced by new cuttings every so often as they get a bit straggly after a few years. They are easily propagated in spring or autumn.