Streptocarpus: Lots of blooms, ease of care
Sometimes commonly known as ‘cape primrose’, Streptocarpus aren’t primrose at all, but gesneriads (African violet cousins). They will bloom heavily year-round and can be quite spectacular. Very easy to grow and bloom, they are great for windows, or in artificial light. Many visitors to our shop will mistake them for orchids, they are so pretty!
Unlike violets, each leaf of a streptocarpus will produce 8-10 or more bloom stalks, sequentially, so that plants tend to stay in heavy bloom for long periods of time. Culture and care of streptocarpus is the same as for African violets. If you are going to grow just one other blooming houseplant besides violets, we would highly recommend trying steps. They are very easy to grow and almost constantly rewarding.
Who we are
We’ve been growing and exhibiting since 1975, and have been in business shipping to satisfied customers world-wide since 1985. We hybridize many of our own plants–are famous for our ‘Rob’s’ and ‘Ma’s’ series of African violets, and our ‘Bristol’s’ series of gesneriads (African violet relatives).
We grow our plants in a renovated barn, circa 1900, with an attached glasshouse and other buildings. At any given time, we have 30,000+ plants being grown. We grow plants because this is what we love to do. View the “about” page to learn more about us.
What we do
We hybridize and grow all the plants we sell–we don’t buy from other growers and resell. This means we know what each plant likes to grow best from personal experience. We also collect the best and most unusual hybrids from other growers, then propagate them for sale, as well as collect and grow many rare species not previously grown in cultivation. We rarely travel or attend a show and come home empty handed!
We also try to share our passion for growing plants with others, and to educate those new to our hobby. We encourage everyone to share their experience with others–the spread the “cheer” and their knowledge. View our “blog” pages or subscribe to our monthly newsletter to read more.
What we grow
We specialize in African violets and their relatives (gesneriads), and other plants suitable for the indoor home environment. Most are of a manageable size (can be grown on a windowsill or light stand), and many will bloom readily in the home.
We also grow a huge, and diverse, collection of miniature and terrarium plants–every plant you need for a terrarium, miniature landscape, or fairy garden. Our plants are true miniatures, not just cuttings of a large plant that will quickly outgrow your container. Safe for use in vivariums. Not harmful to frogs and reptiles. We only use organic, nontoxic, products when growing these plants. For an overview of what we grow, view the “what we grow pages”, or better, our online catalog!
How to grow
Though we’d like to sell you plants (or perhaps we have) use this site as a reference–to learn about the plants you grow (or want to), or to learn how to grow them better. Use our “search function” to answer your question–for example, type “repot African violet”, if this is what you need to know. You’ll be directed to relevant information on this topic, or any other. Our “plant care” pages contain much useful information, including “how to” lessons, and a FAQ (frequently asked questions) library.
If you’ve purchased a plant from us, and are having difficulties growing it, or simply need more information on its care, we can always be reached by email or phone during business hours.
Where to find us
Visit us–our shop and glasshouse are open to the public year-round. Hours and directions can be found in the “about” pages. We also attend (and sell at) a number of shows during the year, throughout the United States. Dates of these upcoming events will be listed in the sidebar at right.
Visit our “facebook” and “pinterest” pages (links found at page top). Subscribe to our monthly newsletter, “VioletsFun”. Join a society–we are longtime members for many plant societies and interest groups. There is no better way to learn than to share your experiences with a fellow grower. We offer incentives to join (a free plant with an AVSA membership) and encourage members to participate and exhibit (coupons for show winners).
Want to share your knowledge or growing experience (or want to educate us)? Many pages of this site allow comments. We’ll post those that are relevant to the page being commented on.
Growing and Flowering Cape Primroses (Streptocarpus)
By Laurelynn Martin and Byron Martin
‘Yellow with Pink Cap’
Cape Primroses, also known as Streptocarpus or Streps, have filled a niche as flowering houseplants for the home for many decades. Their velvety, long green leaves and floral sprays that rise above the foliage create a stunning plant for a windowsill garden.
Streps are known for their ability to bloom in low light. They actually thrive under those conditions. Originally from South Africa, they are found in their native habitat growing on the forest floor; that’s why they have a tolerance to lower light and periods of dryness.
Grown In a Home Environment
Grow in bright shade to partial sun near a window but not in direct southern sunlight (an east or north window is fine). Cape Primroses are also good candidates for a light garden where they will bloom for many months at a time. The leaves, when grown under low light, are deep green whereas when the light is too high, they will develop a yellowish-green coloration.
Streps tolerate drier soil conditions and as a rule it’s best to bring the potting mix to slight dryness and then thoroughly saturate the soil. A slight wilt does the plant no harm. Also, remember to water directly into the soil and do not get the leaves wet, especially with cold water. Cold water on the leaves will stain the leaves and make them unsightly.
Temperature requirements are varied, but generally growing Streps from 60˙F to the high 70’s is hot enough. They will not tolerate high temperatures. This is one of the greatest challenges in their culture. The summer heat, in many areas of the country, distresses the plants and can sometimes cause their collapse. Any type of heat wave, even those that we get in Connecticut, can wreak havoc with Cape Primrose plants. When temperatures rise into the 90’s, the plants will go into a wilt and the leaves get damaged or the plants collapse, as the transpiration of the leaves is far greater than what the root system can uptake.
Flowering is initiated by the intensity of light and Cape Primroses can flower 10 months out of the year in natural light on a north or east-facing window. They also make great plants for light gardens and tend to bloom well under those conditions.
Fertilizing Your Plants
Fertilize with caution since Streps are lower light loving plants. Damage can occur when you use large or frequent doses of high salt fertilizers. When you feed your plant, we recommend intermittent feeding with any liquid, balanced, houseplant fertilizer (where the three numbers are close together or the same). It’s best to reduce the recommended fertilizer dosage by half (so if it calls for one teaspoon per quart of water, add only half a teaspoon per quart). Periodically, you should leach, or let water run out of the bottom of the pot, so you don’t get an accumulation or build up of salt levels from the fertilizer. One of the symptoms of excess fertilization is a browning or burning of the leaf edge as the young leaves emerge and start to grow. As this damaged leaf matures, there will be a burned edge and a constricted area in the leaf. Remember that high temperatures along with greater leaf transpiration can aggravate this problem.
Cyclamen mites and aphids can be a problem when you’re growing Cape Primroses. Cyclamen mites affect the youngest leaves causing a browning or distortion of the growth. Aphids will get on the flowers but only if another infected plant is nearby. We recommend spraying the plants with neem oil, 2 TB per gal with 4 tsp of dishwashing detergent. You’ll need to apply several applications usually a week apart. It’s also best to isolate any infected plants during treatment so the pests don’t spread to other plants.
Root disease can be an issue for Cape Primroses during high temperatures. Since the roots cannot take up enough water during high periods of heat, the stressed root system is the perfect place for disease to set in. If you notice that the plants don’t recover from the wilt they experience on hot days, then tap the plants out of their pots. Diseased roots will be dead and break apart when touched. Rots can also affect the crown at the soil surface cutting off the flow of water. If your home is air-conditioned during the summer heat, then the plants are better able to sustain high temperatures.
Cape Primroses grow in a rosette and periodically the older leaves need to be pinched off if they are yellowing or looking shabby. The old flower stems should also be removed once the flowers have past to keep your plant looking healthy and vibrant.
Streptocarpus parviflorus is a plant that is seldom seen in gardens because of its unavailability in the trade.
Streptocarpus in general, are all very sensitive to direct light, and are burned easily by the sun, but flower poorly in deep shade. Light shade with good ventilation is best for growing healthy plants with plenty of flowers.
Watering streptocarpus should be done with care. It is very important that the plants should not be over-watered to prevent rotting and fungal problems. They have quite shallow root systems, as in nature they often thrive in very little soil, so allow them to get quite dry between watering. In fact, they like being allowed to wilt slightly between each watering, and they have the ability to recover very well from this. Be aware that severe wilting can be a sign of root rot caused by over-watering, so check the soil to see that this is not the case.
Avoid wetting this plant’s leaves, by watering from the base—pour water into the pot tray, so that the plant and soil can absorb what is required from there. During the warm summers when they are actively growing, the plants need regular watering, but note that most streptocarpus ‘rest’ in winter, and this slight dormancy will cause them to need very little water during this time, so be sure to reduce the amount given.
Regularly remove all dead, unhealthy, dying leaves and flowers as these encourage fungal growth, and to keep the plants looking attractive. Removing spent flowers can often stimulate a second flush of flowers.
The tips of the leaves often die off as they get older or when stressed by drought or low temperature or when over-wintering. This unattractive tip can be cut off/removed without harming the growth of the leaf, as it would naturally shed this through an abscission layer and continue with new growth from the base.
Regular feeding during the growing season with liquid foliar feeds, is recommended.
Repot once the plant’s roots appear at the bottom of the pot.
All propagation is best done in spring which is the start of the growing season, Streptocarpus can easily be grown from seed. When sowing the seeds, mix a pinch of the dust-like seeds with a small amount of sand to assist with spreading the seeds evenly. Use a well-drained, spongy medium that is not too coarse. At the Kirstenbosch National Botanical Gardens, we use equal parts peat and compost. Cover with a very thin covering of sand, keep out of direct sun, but in warmth, and water regularly with a fine spray. Germination usually takes 3 to 4 weeks, and do not allow the seedlings to dry out. Plant the seedlings into small pots only once they are quite big and strong enough. Transplant the young plants again into bigger pots when the roots have filled the small pots.
Streptocarpus can be propagated from a single leaf and the best results are from leaf cuttings taken in spring and early summer. Select healthy youngish leaves from the centre of the plant, and cut off using a sharp knife or blade. Remember that the most active region of the leaf is near the base where the growing region (meristem) is present, and so this area will yield the best rooting results. If it is a small leaf, insert the cut end of the leaf into a rooting hormone and then into the medium. Larger leaves can be cut into 3 cm strips. Always take note of which way the leaf cutting should be orientated, before dipping into a rooting hormone, and place firmly into the medium, but not too deep, as this will encourage rot. Alternatively, cut along either side of the midrib and treat in the same manner. A variety of mediums can be used as long as they are well drained. Sand, bark, palm fibre and polystyrene or vermiculite in different ratios are all suitable. At Kirstenbosch we use 40% bark, 40% fine leca and 20% river sand. Water the medium well and treat with a suitable fungicide before using. Depending on the species, plantlets will form along the base of the cut in 1 to 3 months.
When the plantlets are well established, the old leaf can be teased out from the medium and the plantlets potted up into a rich, well-drained soil mixture, usually between 6 to twelve months. Streptocarpus like a nutritious, well-aerated, medium with ample drainage of equal parts loam, sand, peat moss and well-rotted compost.
As they do not have deep roots, they often do better in shallow pots. Plants that have grown quite large can also be divided as a method of increasing them; do this in early spring and repot to grow on. Mature plants can lose their vigour after 3 to 5 years and propagation, as described above, can be used to replace them with younger plants.
Mealybug, aphids and caterpillars are the most troublesome pests of Streptocarpus, though none severely. Caterpillars can either be hand collected or sprayed with a suitable poison, aphids can be sprayed, or removed carefully, by running a thumb and forefinger along the flower stems—where they usually occur; if mealybug is found on any part of the plant, quickly remove the affected parts and treat with a suitable pesticide. Kirstenbosch has had great success in managing infestations by using biological control with the natural predators of mealybug.
Fungal infections are also a cause for concern; if fungus is found on any part of the plant, remove the affected parts and treat with a suitable fungicide.
Streptocarpus are usually only prone to pests and diseases when they are not being treated or grown correctly; any plant that is stressed, is more likely to come under attack. So avoid the following to reduce the occurrence of problems—overwatering, underfeeding, rootbound plants, lack of good air movement/circulation.