Streptocarpus

Cape Primrose

This little forest plant, Streptocarpus or Cape primrose, is indigenous to South Africa. It was first discovered in Knysna in the 1800s and also occurs naturally in the Drakensberg. It is one of our most adaptable and freely flowering garden shade plants. It can also be grown as a houseplant.

Perhaps the name has something to do with it, but it’s hard to know why it is not more popular. Streptocarpus grower Leoné Williams speculates that the plant’s exotic appearance creates the impression that it is fussy and difficult to grow. Nothing could be further from the truth, she says.

What Streptocarpus Needs

Light

Streptocarpus grows easily in dappled sunlight as well as in full shade, as long as there is good light. Too much sun burns the leaves and fades the flowers.

Plants grown indoors should receive plenty of bright light but no direct sunshine, she advises. Plant in fairly shallow, small pots (10cm diameter) and use acid compost or regular potting soil with some peat mixed in as a potting medium.

Water

Regular watering is essential but be careful not to over water because this can cause root rot to develop. Either too much water or too little water can cause wilting leaves. If the plants are in a pot, make sure the potting soil is dry before watering and water less often in winter.

Soil

This plant does best when planted in slightly acid, light and well drained soil, so it’s a good idea to dig in organics like peanut shells, peat, pine needles or bark compost before planting.

Feeding

Streptocarpus benefits from a monthly dose of potassium rich food. Feed once a month with a liquid fertiliser like Nitrosol, Margaret Roberts Supercharger or Multi-feed. You can also use two teaspoons of Epsom salts per 10 litres of water once a month.

Climate

This plant will sail through cold winters. Some varieties may die back but they will sprout again in spring.

Pruning

Cut off dead flowers to encourage the plant to produce more flowers. If you plant produces more leaves at the expense of flowers, it may not be getting enough light or may be receiving too much fertiliser.

Pests and Diseases

Pests and diseases are not something you will have to worry about when it comes to Cape primroses. They are remarkably free from pests and diseases.

Propagating Streptocarpus

Streptocarpus propagates easily through leaf cuttings. Simply take a fresh young leaf from the centre of the plant and place the cut end in a mixture of equal parts of compost and vermiculite or perlite. Cover the pot with a plastic bag and put it in a shaded place that is well lit. Keep the medium damp, but not sodden, and within a month the cutting should have rooted and a new plant will grow from the base. Read more about how to propagate streptocarpus in this article.

Varieties to choose

There are many different hybrid varieties, ranging in colour. It comes in all shades of blue, which is the most common flower colour for these plants. You can also get some with flowers of maroon, pink and white. Gardeners wanting to establish an indigenous wooded garden can combine them with Plectranthus and indigenous ferns because they have the same kind of soil, moisture and light requirements.