Plectranthus is the largest South African genus in the mint
family (Lamiaceae), with 44 species natural to our region, most
of which occur on the eastern side of the country. Plectranthus
ecklonii , seen above, was described as Plant
of the Week a few weeks ago.
species are narrowly endemic occurring only in a very limited area,
while others are widespread and very variable and consequently difficult
Among the South African members of the genus we have some of the
showiest garden plants providing a mass display of colour in late
summer and autumn. Colour selections range between pink, purple
and white and many shades in-between. Although there are two species
which do have yellow flowers they are not good garden plants and
their flowers are too small to be attractive.
Plectranthus are noted for their aromatic leaves when crushed or
even brushed against, and the variety of aromas is as diverse as
the genus itself.
are easily cultivated and require little extra attention or special
treatment. They enjoy well-composted soils, and as rule thrive in
semi shade or cool positions on south facing aspects. They are ideally
suited to growth under the shade of trees. They are generally shallow
rooted and enjoy adequate water but they do store water in their
stems and are resistant to prolonged periods of drought. Plectranthus
are often grown for their attractive foliage, flowers or both and
vary in their growth forms from dense prostrate ground covers to
sub-shrubs and large shrubs.
Although they are frost tender they are usually grown in shady
protected places and as such are afforded some protection from frost.
Due to the fact that they all flower at the end of the growing season
frost does not affect flowering. If the plants are affected by frost
they can be cut back at the end of winter and will grow out rapidly.
Once the plants have been established for a year or more they become
woodier at the base and are more resistant to frost damage.
of the shrubby species make better, more dense and attractive shrubs
if they are pruned back to between 1/3 and 1/4 of their height,
at the end of winter before the new growth begins for summer. After
pruning is the ideal time to dress the soil with a thick layer of
compost or organic mulch and an application of balanced fertilizer
such as 2:3:2.Ground cover species rarely need to be pruned, other
than occasional cleaning up of old growth and flower spikes.
The ground cover species often have very attractive foliage and
form dense attractive carpets from 150mm to 450mm thick, which burst
into flower in autumn. They root readily at the nodes wherever they
touch the ground, and will form dense mats in a relatively short
Shrubby species vary in height from 0.5 - 2m and may be planted
en-masse or as single individuals Once again most species enjoy
shade but there are a few which can endure full sun.
Plectranthus are exceptionally easy to propagate and can be produced
very easily with little special treatment. Most propagation is done
from cuttings during the early part of summer and spring. Although
the cuttings will root at any time of the year, they have a long
summer ahead to establish if they are propagated at this time. Cuttings
may take the form of soft-wood, semi-hardwood, but tip cuttings
are usually the best.
The cuttings should have at least two nodes and the leaves should
be removed from the lower portion. Rooting hormone is usually not
necessary and has been known to cause the cuttings to rot. The cuttings
should be inserted one third of their length into clean double washed
river sand and kept in a warm shady place and not be allowed to
Witwatersrand National Botanical Garden