Cape Plumbago (Plumbago capensis)

Arabic name: أزرق ياسمين

Although 12 species of Plumbago are known from the warm regions of the world, it is the South African Cape Plumbago (Plumbago capensis), which is most usually planted, and with which most of us are familiar.  There is no other flower that has the same sky-blue color, and a large specimen in full flower during summer is a lovely sight. 

Cape Plumbago is very tolerant of heat and drought.  This evergreen vine or shrub is a very popular, extremely reliable, and resilient plant.  Trusses of sky-blue flowers are carried from summer to early winter, as Cape Plumbago blooms all year long except for the coldest winter months.  Unsupported, it grows into a sprawling, mounding bush, with fresh looking light to medium green leaves.

Well known for its bright pale blue flowers, this rampant spreading shrub or vine will quickly transform a garden corner.  It is very useful in large gardens as it forms suckers and will cover fairly big areas.

Cape Plumbago grows to a height of 3.0m, with a spread of 1.5m.  It is fast growing, taking six months to one year to reach its mature size.  Its flowers bloom from May to October.

Requirements: Grows in full sun.  Flowering will be reduced in partial shade.  Needs fertile, well-drained soil. 

Water usage: low watering (twice a month).

Appearance:  It is an evergreen shrub with gracefully arching semi-woody stems that form a loose, rounded mound.  The 5cm oblong leaves have a fresh, green color.  New growth is a bright green that turns darker when mature. The sky-blue flowers are 2.5cm long tubes expanding into 5 petals spreading about 2.5cm across.  The flowers are borne on rounded terminal clusters 15cm across.  A white-flowered variety is available, as is a lower-growing cultivar with deeper blue flowers.

Notes on use:  Suitable as a shrub, groundcover, or vine.  It can be used in borders, foundation plantings, and for color massing in beds.  Also, it can be used as a background or filler plant under and in front of shrubs that have stronger frameworks.  Its rambling habit makes Cape Plumbago highly suitable as a flowering groundcover.  Space plants at 0.9 – 1.2cm intervals for a solid mass at maturity.

Propagation: Propagate by rooted suckers from the mother plant, or by semi-ripe cuttings in summer.  Can also be grown from seed.

Potting: Makes a nice container plant that spills over the sides, with arching stems carrying the clusters of flowers. 

Maintenance:  Cape Plumbago can be pruned to grow like a vine, or into a more compact mounded shrub, or left to sprawl with its long branches.  It makes a very good informal or formal hedge as it responds well to pruning.  To keep it neat and within bounds it should be pruned heavily.  This makes it bushy to maximize the number of flowers.  It will flower profusely after being cut back, or after a growth flush, as it bears flowers on new wood.  Therefore, thin out or cut back all the previous year’s growth in early spring.  Fertilize when new growth appears.

Notes:  Cape Plumbago is attractive to birds and also butterflies.

This article is part of a series of articles prepared by the Center for the Study of the Built Environment (CSBE) on water conserving landscapes. 

For additional information on water conserving gardens, visit the CSBE web site at www.csbe.org

Support for the CSBE project on water conserving landscapes is provided by WEPIA (Water Efficiency and Public Information for Action), a program being implemented in collaboration with the Ministry of Water and Irrigation and funded by the United States Agency for International Development (USAID).