An Introduction To Streptocarpus House Plants

Streptocarpus are not commonly available and most gardeners either have not heard of them or they know very little about them. I was one of these gardeners not that long ago but now that I have some experience with them I can’t believe they aren’t more popular. They grow in fairly low light, are easy to take care of and flower 12 months of the year. They are also available in hundreds of colors and flower shapes including singles, doubles, straight edged and frilly edged. Some of the newer hybrids don’t even look like streptocarpus.

In this post I will introduce you to streps, as they are commonly called.

What Are Streptocarpus?

Streps are related to the very popular African violet and grow in much the same way. They belong to the Gesneriad family of plants which also includes the gloxinia. The name streptocarpus refers to it’s twisted seed pod (streptos is Greek for twisted and carpos for fruit). Their common name, Cape primrose is probably based on the fact that they have leaves that look similar to primulas which also originate from Africa. Streps and primulas are not related. 

The streps grown as house plants are usually hybrids. They form a tight rosette of leaves with each leaf having a short stem that connects it to the crown of the plant.

Streptocarpus Flowers

The plants are grown for their flowers which are reminiscent of orchids. It generally has 3 lower lobes and 2 upper lobes. These two sets of lobes can all be the same color, or they can have different colors as in this one, called Yellow Pink Cap.

The flower has two anthers, each arising from one filament. In a new flower they are joined loosely together and as they mature they open up and “act like a pepper shaker, which means that not all the pollen is released at once”. The stigma is located deep inside the flower and grows in length as the flower develops over several days. It generally becomes receptive to pollen after it’s own pollen has been released, thereby reducing the chance of self pollination.

Fairly long stems hold the flowers well above the plant and each stem can have multiple flowers, making for a long display. Plants with smaller flowers tend to have more flowers on each flower stem. The Grape Ice pictured above had 50 flowers and 20+ buds when the picture was taken.

Flower stems originate at the base of leaves and each leaf can produce three to nine flower stems depending the cultivar, the size of leaf and on the health of the plant. Some cultivars can produce 40 or more flowers from a single leaf.

Propagation of Streps

One of the fun things about streptocarpus is that they are easily propagated. Large clumps can be divided into several smaller clumps. A leaf or even part of a leaf can be used to make new plants which will take about 4 to 6 months to flower.

Streps are also easily propagated from seeds although the seed is very small and looks like well ground pepper. They germinate easily in about 2 weeks and can be flowering size in 6 to 8 months.

The History of Modern Streps

The Innes Center has done a good job documenting the development of the modern streptocarpus in England. I’ll just offer a few highlights and also look at development in other countries.

The first species of Streptocarpus, S. rexii, was brought to Kew in England in 1818. A second species S. saundersii was introduced in 1861, a third S. parviflorus in 1882 and a fourth, S. dunnii, flowered at Kew in 1886.  That provided enough genetic material to get breeding started.

William Lawrence, who was working on the genetics of color inheritance at John Innes, did a lot of the early breeding and the first modern strep with a flat face, called ‘Constant Nymph’ was released in 1946. It’s name reflects the fact that this was one of the first hybrids that had a long flowering period, April to November and even longer if kept in bright light. This cultivar is still available today.

By 1970 the only colors that were available were blue and white. Then (Andrew) Gavin Brown started work on introducing more colors including pinks and reds. In 1972 John Innes released its first batch of seven new varieties of streptocarpus named; Diana, Fiona, Karen, Louise, Marie, Paula and Tina. Later Brown developed further varieties, both by traditional breeding methods and by X-ray and chemical-induced mutation.

Further development by Dibley resulted in the release of Crystal Ice in 2000. In 2010 Dibley’s nursery in Denbighshire won Chelsea Flower Show’s coveted ‘Plant of the Year’ Award for its new Streptocarpus variety, ‘Harlequin blue’- the first flat-flowering, bicolored Streptocarpus.

The rest of the world was also busy breeding new streps. Much of this work was done in Eastern Europe with some excellent breeders in Poland, Ukraine and Russia, and they have introduced a wide range of colors and flower forms. Much of their work has been focused on making the flower larger. Excellent breeders have also been working in the USA and some of them are producing smaller mini-streps.

The variety of plants on the market today is mind boggling and yet the general gardening public are mostly unaware of them. I predict that in a few years you will find them next to African violets and orchids in your local grocery store.

Naming New Cultivars

The official registry of new streptocarpus names is The Gesneriad Registry. Unfortunately, it has not be very active recently and breeders are not using it. Instead breeders are putting a prefix (more common in USA) or a suffix (common in Europe) on the cultivar name. For example, I use the prefix “RP” in my names, as in Streptocarpus RP Fuchsia Sunset.

You can find a table listing streptocarpus breeder codes here.

Growing Streptocarpus

I am not going to go into detail here, but the link below will take you to a series of videos that provide the basic information your need. The most important thing to remember is that these plants grow in relatively dry locations in the wild. They can take some drying out, but they can not be too wet. Use small pots, plant them high so the crown is dry, Use well drained media and DO NOT OVER WATER. If you get the watering right, you will have no trouble growing them.