Temperature: 65-80°F degrees. Low 60s usually induce more leaf variegation and white flowers in some varieties.
Light: Half shade or artificial light (5000 to 10,000 lux) for 8 hours a day.
Watering: Bottom water with room temperature water when the soil looks dry and light colored. African violets can be watered from the top, however the water temperature should be warm and the leaves should get dry as soon as possible. Cold/hot water will damage the leaves.
Soil: Peat moss (I use Promix HP) with 20-30% perlite. If wick-watering, use more perlite. African violets need to be repotted every 6-12 months with fresh potting mix. Miniatures should be repotted every 3-6 months. Old roots, leaves and stem should be removed to encourage new root growth, otherwise the plant will not bloom well and will develop a long “neck”.
Fertilizer: Dyna-Gro Foliage Pro or Dynagro 7-9-5 at ¼ of the recommended strength with each watering. There is no need for “bloom boosting” and high middle number will be harmful to the plants. The secret to blooming is sunlight.
Pot Size: Standard violets: 2.5-4 inch plastic pot; Miniature violets: 2-2.5 inch plastic pot; Mature streptocarpus: 4-5 inch pot
Avoid deep pots, because violets won’t bloom well until they get root-bound and a deep pot may increase the possibility of root rot.
Humidity: Young and baby plants need 80-100% humidity, while mature plants can grow well in 40-60% humidity.
If you need to learn more details about growing African violets, I strongly recommend reading the book Growing to Show: How to Grow Prize Winning African Violets by Pauline Bartholomew.