Cape leadwort

Cape plumbago is native to South Africa’s southern and eastern regions and grows as a scrambling, informal screen wherever the winters stay mild, flowering in sky-blue clusters for most of the warm half of the year. Drought resistance is one of its most reliably confirmed traits, which makes it a genuine water-wise choice for a hedge or screen rather than a plant merely marketed that way.

Light

Full sun, morning sun or afternoon sun are all workable. Too much shade is the main reason a plumbago stops flowering, well before soil or water become the problem.

Water

Confirmed drought resistant once established, though it flowers more freely with a deep, regular water through summer than left entirely to fend for itself. Keep it on the dry side over winter, when it is doing far less growing.

Feeding and pruning

A slow-release fertiliser, or a balanced feed through spring and summer, keeps the long flowering season going. The defining pruning instruction, confirmed by South African growing guides, is to cut it back hard at the end of winter, before new growth starts, since it flowers on new wood and takes its hardest cut well at that point in the year. Avoid a similarly hard cut at any other time, since that removes the growth the coming flowers would have come from.

Propagation

Semi-hardwood cuttings taken in summer or autumn root reliably, and lifting a rooted sucker from the base of an established plant is, by more than one account, the easiest method of all. Seed sown in spring also germinates readily.

Growth habit and where to use it

It naturally scrambles rather than standing stiffly upright, which suits it to an informal screen or a loosely trained wall shrub more than a tightly clipped formal hedge, though regular clipping keeps it dense enough to work as one if that is what a garden wants. Left largely alone it reaches around three metres in each direction, but it takes readily to being kept much smaller, down to about a metre, with regular light trimming through the growing season on top of the hard end-of-winter cut. In a marginal climate its frost tenderness is worth planning around the same way as Duranta’s: a plant cut to the ground by a hard frost is not necessarily dead, and usually regrows quickly once the weather warms. A large pot is a reasonable compromise in a garden that gets occasional hard frost, since it can be moved under cover for the worst of the winter and still spend the growing season outdoors doing the job an in-ground plant would rather than living permanently indoors.

Ailments

Mites cause a fine webbing across the growth tips in hot, dry, still weather, and regular hosing down of the foliage discourages them before they need a spray. Cottony cushion scale is the other common problem, recognised by the honeydew and the sooty mould that follows it, and a thorough spray of horticultural oil clears both.

One caution is worth stating plainly rather than glossing over. ASPCA has no rating for this exact plant, and two of its pages that share the common name “plumbago” belong to a different genus entirely, rated non-toxic; that rating should not be borrowed for this species. Separately, a 2016 veterinary case report describes a dog developing a painful, blistering skin reaction after contact with this plant, caused by a compound in the sap called plumbagin. That is a contact reaction rather than a poisoning from eating it, but it is a real, documented risk worth knowing before handling or pruning it bare-handed.