As with many houseplants, African violets have specific watering needs. Water that is too cold can shock warm leaves and cause white or yellow spots or streaking. Water that is at room temperature or slightly warmer is best. Regular drinking water is adequate for watering if it sits out until it come to room temperature. Don't let the soil get so dry that the plant wilts before watering. Before watering, test the moisture level by sticking your finger 1 to 2 inches into the soil. If it is dry, go ahead and water, soaking the soil. Don't let African violets stand in water.
African violets can be watered from the top or the bottom. To water from the top, use a watering can or container with a spout to avoid dampening the foliage, especially if the water is cold. Soak the soil and discard any water that trickles to the drainage dish. Bottom watering is the best option, as this method avoids contact with the leaves altogether. If you water from the bottom, the temperature of the water is not as important. Fill a dish with water and set the African violet pot in it. Allow the soil to soak up water until it is thoroughly moist and then remove any excess water in the dish.
Proper drainage is an important aspect of African violet care. In addition to the sensitive leaves, the roots are highly susceptible to root rot. Sitting in excess water can be a death sentence for an African violet. The University of Florida recommends a mixture of equal parts peat moss, vermiculite and perlite for the best results. Clay or plastic pots are both acceptable; plastic pots don't allow for as much evaporation and require less frequent watering. Plant your African violet in a pot with adequate drainage holes.
Along with proper watering techniques, African violets need just the right amount of light for prolific blooming. A bright spot in your house is best for African violets, but they can't tolerate afternoon sun. Daytime temperatures of between 80 and 85 F with nighttime temperatures between 65 and 70 F are optimal for African violets. Yellowing leaves and reduced growth could indicate fertilizer is needed. Formulations specifically for African violets are commercially available.