Karoo Desert National Botanical Garden
The Garden Through the Seasons
The Karoo Desert NBG is 154 ha in extent, with
a developed area of 11 ha, and falls within the winter rainfall area of South
Africa. Summers are hot, up to 40°C, whereas winters are cool and wet, with
light frost in the lower reaches of the garden. Minimum temperatures of 2°C
have been recorded. Constant wind is experienced, especially during the winter.
The
garden has a number of sections for displaying the horticultural potential
of the various desert plants. These are mainly plants grown for their brilliant
flower colour or sculptural forms. Nearly 90% of plants grown are of a waterwise
nature!
The
best time to visit the Karoo Desert Garden is in spring, when Namaqualand
daisies (Dimorphotheca), Bokbaai vygies (Dorotheanthus), Gazania, Ursinia, Felicia, and Arctotis all look their best. The actual peak flowering time depends
very much on the rain—when it falls and how much falls—but generally, August
to early September are the best months. The perennial vygies, Drosanthemum and Lampranthus, are at their best in early October. By November, most
of the annuals and vygies are past their prime. Spring bulbs in flower at
this time include Freesia,
Tritonia, Lachenalia, Ornithogalum, Sparaxis, Babiana,
and Bulbinella
Spring
and early summer are ideal times to take advantage of the garden’s many nature
walks. December to February are the dry, hot months of the year, but many
hardy karroid trees have been planted in the car park and on the upper lawns.
These in time will give shade to the weary visitor. During summer, some of
the red and pink Crassula species
are in full flower. It is during these hot months, when the natural Karoo
veld takes on a pale green hue, that fires become our biggest threat. The
Karoo veld, when devastated by fire, can take up to 30 years to recover!
Autumn
is the time when many of the dormant summer bulbs push out their massive round
heads of flowers. From March until May the bulbs flowering include Brunsvigia,
Boophone, Cyrthanthus, Haemanthus, Nerine, and Amaryllis
From
early March until the end of May, the following genera are in flower—and characterized
by their smell of rotten meat—very noticeable on hot, balmy afternoons: Stapelia,
Duvalia, Piaranthus, Hoodia, and Huernia
Autumn
is also the time when many of the mesembs are in flower. These chunky succulent
plants, all of which make ideal pot plants, look their best after the hot,
dry summer months. Their iridescent flowers are spectacular against the stone-like
leaves: Lithops (stone plants), Conophytum (resembling stone plants), Pleiospilos (liver plant),
Dinteranthus, Argyrodermas,
and Lapidaria
During
the winter months, the days are short. The first snow of the season has already
fallen on the Brandwacht Mountains to the north of the gardens. Rain falls
sporadically, often accompanied by strong northwesterly winds. The attractive
display of Oxalis (clover) makes
a visit to the garden rewarding. These cheerful plants flower in an array
of colours including pink, yellow, white, mauve, and purple. The warm colours
of the many flowering aloes also brighten the dullness of winter. Aloe dichotoma and Aloe ramosissima with their bright yellow flowers and pale, flaky
bark stand out like beacons in the wintry landscape. Other noteworthy aloes
include Aloe ferox (Medicinal Aloe),
Aloe barberae, (the Giant Tree Aloe
from the eastern Cape), and
Aloe plicatilis (Fan Aloe)
Some
of the vygie species start flowering from early winter through to spring.
The mat-forming Cephalophyllum species
provide especially vivid displays with their metallic red, magenta, yellow,
and pink flowers.
Natural Vegetation
According to Dr
Tim Hoffmann in the Vegetation of South
Africa, Lesotho and Swaziland, the Karoo Desert Garden falls within the
Little Succulent Karoo. The region occurs in the hot, dry valleys between
the two parallel east–west trending mountains of the Cape Fold Belt. The physical
geography, locality, climate, geology, and soil create the ideal conditions
for a succulent-rich flora.
The
natural vegetation is characterised by small karroid bushes, hardy geophytes,
and succulents. Some 422 species grow naturally on the estate; most are succulents.
Beautiful geophytes are abundant, including Nerine spp., Massonia spp., Ornithogalum spp., and Brunsvigia
josephinae
The
shrubby plants are mainly of the family Asteraceae. Perennial shrubs include
Pteronia Elytropappus (Rhino Bush), Galenia Rhus, and Eriocephalus
Euclea (Gwarribos)
Plants
of a succulent mesemb nature include Antimima mucronata,
Conophytum ficiforme, Drosanthemum bicolour, D. speciosum,
D. micans, D. striatum, D. thudichumii, D. barkwickii,
Ruschia carolii, R. multiflora, and R. pygmaea
Other
notable succulents are Aloe
microstigma, Cotyledon orbiculata,
Crassula
(25 species), Euphorbia
burmannii,
E. mauritanica,
Haworthia herbacea
var. herbacea,
H. pumila, Orbea
variegata,
Othonna retrofracta,
Senecio radicans,
Quaqua mammilaris,
and Tylecodon paniculatus
Trails
There is a
network of pathways in the natural areas, approximately 8 km long. These pathways
are connected to the Fairy Glen hiking trail. There are three trails with
information/story/picture boards:
The
Braille trail, 400 m long
The
Shale trail, 1,000 m long
The
Karoo Adventure trail (including the new Bushmanland section of 2 ha)
Future Development
Plans
We have eight plans in implementation:
5,000
m˛ Aloe
dichotoma (Quiver Tree) forest/Bushmanland area. The garden has received
financial support of R40,000 for this project from the Kirstenbosch Branch
of the Botanical Society. The project is well under way with 300 young Aloe dichotoma plants having been planted. We plan to rescue another
200 young Quiver Trees during 2002/2003,
bringing this project to its conclusion.
1,000
m˛ Aloe
barberae (Bains Aloe) forest. These will be grown from cuttings or seed
if available, and will be planted during the winter of 2002.
Further
development of Karroid phytogeographical areas.
Development
of a Pelargonium hillock, featuring
mainly succulents and species from arid areas.
Automated
irrigation on all lawned areas.
Arboretum
featuring the trees from the dry areas with emphasis on Acacia.
Re-establishment
of Aloe pillansii in South Africa
and Namibia (Richtersveld). Mortality is extremely high, with a large percentage
of mature trees dying. Recruitment of new seedlings has been sparse in places.
This is a joint SANBI/NBRI
(Windhoek) project.
Construction
of an additional glasshouse for cultivation of Aloe species.
Rare and Endangered Species
Of the 3,700 taxa
growing in the Garden, 340 species are recorded as rare or endangered. Over
60% are succulents. Rare and endangered plants are propagated and offered
for sale in an attempt to take the pressure off populations in the wild.
Visitors
The Karoo Desert
National Botanical Garden has a lot to offer visitors. It must surely be one
of South Africa’s largest waterwise gardens. Some of our special features
include the following:
Display
of arid plants, indigenous to southern Africa
One
of South Africa's biggest waterwise gardens
The
Index collections of succulents
The
Xhosa herb garden
The
Nama cooking shelter and herb garden
Portulacaria afra and plant
maze
Karroid
phytogeographic sections
Collections
of caudiciform plants
Spring
colour (annuals and vygies)
Shop
and plant sales where unusual desert plants, seed, and botanical books are
available for sale
Largest
artificial Quiver Tree forest in the world
The
Garden receives approximately 34,000 visitors per year, and staff members
conduct guided tours for 85 groups per annum. Of these, approximately
60% are international visitors.
—by Ian Oliver
SABONET News 7.2: 120
go
back to South Africa main page
OLIVER
I.B. 1993. The Karoo National Botanical Garden—showpiece of the Bree River
Valley and gateway to Namaqualand. Veld
& Flora Vol. 79(2): 46–48.
OLIVER
I.B. 2000. A unique desert garden in the winter rainfall area of South Africa.
Aloe. Vol. 37(2,3): 28–30.
