Problems with African violets include failure to flower, petiole rot, water spots, diseases such as crown and root rot, and pests infestations. Failure to flower occurs when the soil is too wet or the weather is too dry. Instead of opening, the buds turn brown and fall off.
A rust-colored spot where the leaf stem touches the pot is symptomatic of petiole rot. Fertilizer salts accumulating on the pot rim and soil surface cause the rot; too much fertilizer often causes the accumulation. Watering with rainwater is one way to avoid this condition. It also helps to tape the pot rim. Flush the pot with lots of water to drain out the salt in the soil.
Cold water causes water spots, which are ring and line patterns that are white or yellow. To avoid this problem do not get the leaves wet when watering the plant.
Crown and root rot is fungal and occurs with too much watering, planting too deep or lacking proper drainage. As a result the crown and roots turn mushy.
Cyclamen mites are too small to be seen. An infestation of these pests stunts the leaves in the center of the plant, and new leaves tend to be very hairy and grayish. Mealybugs suck on plant sap. Their feeding blocks growth and disfigures the leaves. Plant death occurs with serious infestations.
Pests are some of the biggest problems for African violets, and their presence can be minimized by disinfecting any materials that may come into contact with African violets. Tools can be disinfected by soaking them in a 10 percent bleach solution, and Optimara recommends hand washing. After working outside, change clothes before working with African violets. Outdoor pests have been known to stay in clothing until they gain an opportunity to target indoor plants.