Botanical Name: Gesneriaceae Streptocarpus
Other Names: Cape Primrose, Streptocarpus saxorum, Streptocarpella saxorum
- Type: Perennial
- Height: 12-18 in. ( 30-45 cm)
- Zone: USDA Zone 9 - 11
- Popular Varieties: Weismoor Hybrids, Windowsill Magic, Dibley’s Series, Bristol’s Series
Streptocarpus are easy growing perennials in warmer zones. They prefer partial shade but can tolerate up to 5 hours of direct sunlight per day (less in low-humidity environment).
How to Grow Streptocarpus as a House Plant
Streptocarpus are wonderful house plants, blooming freely throughout the year. Their care and cultural requirements are similar to those of African violets with a few minor adjustments. The following are general guidelines for growing Streptocarpus plants in the home.
Temperature
Streptocarpus prefer moderate temperatures in the range of 65 - 80 degrees Fahrenheit. They are not as heat-tolerant as African violets and like more humidity, if possible. Use pebble trays to increase ambient humidity. Streptocarpus leaves tend to get “crispy” on the edges in low-humidity situations or if plants are allowed to dry out between waterings. If that happens and you find it unsightly you can cut off the tips of the leaves with scissors without harming the plants. (You can do this with other house plants, as well, such as spider plants and Dracaena which tend to get ‘leaf burn’ at the tips.)
Air Circulation
Adequate air circulation is important for all house plants if you want to avoid problems such as molds and powdery mildew. Space plants apart from each other and add a small fan to rooms with poor air flow.
Light Requirements
Streptocarpus grow well in natural light and prefer some direct sunlight. Three to five hours of morning sunlight works well for most growers. Streps can also be grown successfully on lighted plant stands using regular fluorescent tubes (cool light). Place plants 8 to 12 inches from the lights for 12 to 14 hrs per day. More or less light may be required depending upon other environmental factors and you may want to experiment.
Watering
If you grow Streptocarpus in potting soil water approximately once a week in winter, twice a week in summer or as required &emdash; plants should not be allowed to dry out completely. If you have poor quality tap water or your water contains additives such as chlorine, chloramine, or water softeners we suggest you use filtered or bottled water. Additives can inhibit growth or blooming in flowering house plants and ornamental plants.
Fertilizing
Fertilize your Streptocarpus with a weak solution (1/4 strength) of a balanced fertilizer each time you water. Alternately, use a half-strength solution twice a month.
Growing Streptocarpus from Seed
Streptocarpus seeds are extremely small - one ounce of strep seed contains approximately 2 million tiny seeds. Streptocarpus have the same germination requirements as African violets, Sinningia speciosa (Florist Gloxinia) and other gesneriads. Strep seeds need light in order to germinate and should not be covered over with soil. Follow these instructions to successfully grow streptocarpus plants and similar gesneriads from seed.