A well-grown Streptocarpus (cape primrose) is a joy. The many hybrids provide pleasing colors and dashing combinations in shades of crimson, pink, blue, violet and white.
Contrasting lines and blotches of vibrant colors radiate from the throats of the flowers to add interest.
The natural habitat of streptocarpus is principally in Africa and Madagascar. There they grow in cool, humid, wooded mountain ravines where sheltered humus provides moisture for the roots.
The word streptocarpus is not as puzzling as it looks. It is a combination of two Greek words, streptos (twisted) and karpus (seed pod). The twisted seed capsule, on most varieties, is longer than a toothpick and nearly as thin.
The First Streptocarpus Arrives
The first streptocarpus species collected was brought from the African estate of George Rex, and it bloomed in England’s Kew Gardens in 1826.
This gloxinia-like little plant received a generous welcome and was soon named Streptocarpus rexii. It develops compact rosettes of fluted, dark green leaves.
From the axils of these come six to eight-inch stems, each holding one or two tubular flowers of rich blue. Today, this species figures in the background of many outstanding hybrids, such as the Weismoors, and is still grown by collectors.
At least two species of streptocarpus, S. wendlandii and S. grandis, develop only one large leaf. It matures in a year or more when numerous flowering stems come from the base of the strong mid-vein of the leaf.
These individual leaves may grow to two or three feet in length when the plant is given abundant moisture.
I experienced this when growing S. wendlandii in a specially prepared border north of my house.
Even the width of the leaf was 12” inches. Imagine the problem encountered at potting-up time before frost!
I solved the dilemma by using a large pot and placing it on a table on the porch where the leaf could rest in its natural position.
However, now I am growing S. wendlandii and S. grandis in four-inch pots and the leaf measures about 18” by eight inches, and they seem content in this size pot.
S. grandis has a leaf of lighter green than that of S. wendlandii, and it is thinner.
These streptocarpus are annuals – they bloom once, then die.
The Leafy Stem Cape Primrose Streptocarpus
Another streptocarpus group is composed of species with erect, leafy stems.
The most familiar is Steptocarpus saxorum, seeds of which were brought to the United States from Tanganyika (present-day Tanzania) by L. J. Brass of Florida in 1950.
It is easily grown and propagated.
I’ve grow it in an east window and even in a south window during winter while the sun is far south. The sun brings out the dainty blue flowers, each held by its own wiry, three-inch, red-black stem.
When these appear in profusion, they are suggestive of arms reaching out to wave blue flags all around the plant.
Streptocarpus saxorum is a branching plant with a multitude of stems. The largest individual leaves are slightly less than an inch long, and about one-half inch wide.
They are succulent and hairy. Stem cuttings root well in vermiculite, in a mixture of peat moss and sand, or in a combination of peat and perlite.
Streptocarpus kirkii of this group has branched stems and heart-shaped leaves about 1 ½” inches in diameter. Each flower stem may hold as many as 25 or more light blue blossoms.
Cape primrose may be propagated by seeds or cuttings just as easily as African violets.
Also, the same soil African Violet soil mixture may be used.
Good drainage is necessary, but the soil should never dry out or the leaf edges will turn brown. Streptocarpus resent air that is excessively hot and dry.
In the window garden, it helps to set them on a surface of moist sand, peat moss or perlite.
S. rexii and the other hybrids may be grown at cooler temperatures than are usually provided for African violets and gloxinias – down to 50° degrees Fahrenheit at night.
Give them plenty of sun in winter.
The one-leaf species, S. wendlandii and S. grandis, have done well for me in a wide range of conditions, seeming to thrive best with a moist atmosphere, and a temperature range of 62° to 75° degrees Fahrenheit in the winter.
S. saxorum needs warmth, some sunlight and high humidity.
I have found streptocarpus valuable in my outdoor garden during warm weather.
The roots seem to appreciate the opportunity to meander deeply into moist leaf mold. Early morning and late afternoon sun promote compact growth and profuse flowering.
Watering is done with a flared hose nozzle, and on extremely hot days the plants are cooled by the hose several times a day.
During the summer, streptocarpus outdoors relish the dew, rain and cool night air.
By Florence Knock