Streptocarpus plants thrive indoors in containers, if they have temperatures between 10.0 and 32.2 degrees C and bright light, though not direct sunlight. Choose from a variety of hybrids that grow compactly and produce flowers in blue, violet, red, pink or white. Also called Cape primroses due to their origin on the Cape of Good Hope, streptocarpus are similar to African violets. They're sensitive to excess heat and improper watering and will wilt under the wrong conditions.
Check the temperature of the room where you have the streptocarpus using a thermometer. If the temperature is over 32.2 degrees C, move the plant to a location in the range of 15.5 to 26.6 degrees C. Keep the soil barely damp but be careful not to overwater while the plant is recovering.
Feel the soil below the surface by gently sticking your finger down a few inches. If the soil is wet and the temperature is under 32.2 degrees C, the streptocarpus may be wilting from over-watering or poor drainage. Discontinue watering it until the soil is almost dry and, if necessary, repot it into soil with better drainage. If the soil is dry when you first feel it, the plant may be wilting from too little water. Water the plant by filling the pot's saucer and letting the soil soak up the water from below. Pour out any excess water from the saucer after an hour or two.
Prevent future wilting by letting the plant soak up water from its saucer rather than watering it from above. Keep the soil damp to the touch but don't overwater until it becomes soggy. When temperatures approach 32.2 degrees C or if the plant stops growing in cooler temperatures, water it less, keeping the soil barely moist.
If you're concerned about how much to water, give the plant too little, rather than too much. "Streptocarpus should rather be under watered than over watered," according to Liesl van der Walt's article on Streptocarpus at PlantzAfrica.com, a website of the South African National Biodiversity Institute. "Even when slightly wilted from drought, they will quickly recover with a good watering."