Plectranthus hail from warm temperate to tropical areas of the world 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.
Sometimes called 'silver plectranthus', Plectranthus argentatus is an Australian native rainforest plant which adds dainty spires of tiny autumn flowers in lilac calyces to the year-round beauty of its large plush-velvet leaves. It grows about 1m tall and tends to sprawl sideways a fair bit. It is one of the few silver-leafed plants to enjoy shade, including dry shade. It can form a broad pool of silver, which enhances any neighbouring leaves or flowers, but it looks particularly beautiful in association with white flowers, such as Impatiens, Japanese windflowers, cane or shrub Begonia and Hydrangea. It looks dramatic with dark leaves, such as black mondo grass (Ophiopogon planiscapus 'Nigrescens') or black-leaved taro (Colocasia esculenta 'Black Magic'); or with the lovely purple and silver foliage of Strobilanthes dyeriana (pictured above). It will also grow very successfully in dry, sunny positions, making it a versatile garden plant in subtropical-style gardens with Salvia, Dahlia and Canna.
It needs to be cut back quite hard in late winter. Like most Plectranthus it is frost sensitive, but survives most winters in Sydney, and if grown under a tree, this will give protection in very cold suburbs. It is easily propagated by cuttings and also tends to self-seed to some extent. All Plectranthus need to be replaced by new cuttings every so often as they get a bit straggly after a few years. There is some variation amongst the plants, with some having pale blue flowers; and there is a more compact form around, called 'Silver Shield', which grows to 60cm and is less sprawling. The groundcover Plectranthus 'Nicoletta' has similarly furry silver leaves but I don't think it is related to Plectranthus argentatus.