Overwatering African violet plants can lead to disease, such as root or crown rot, and can also cause denitrification in the African violet, which occurs when the violet is robbed of nitrogen that is vital for its survival. By keeping your African violet plants properly watered, though, you can have healthy violets that continue to thrive and bloom.
Fill a plant saucer with room temperature water and set the African violet’s planter into the saucer. If you do not have the African violet planted in a planter with holes in the bottom, replant the African violet into a planter with holes.
Leave the African violet planter sitting in the water for up to 30 minutes. After 30 minutes, remove the planter from the water even if all of the water has not been absorbed.
Water your African violet plants again once the soil feels dry to the touch. The proper watering schedule for African violet plants is approximately once per week. The goal is to keep the African violet plant’s soil moist at all times, but to never make the soil soggy.
Do not use tap water for your African violets if you have soft water as soft tap water can have a negative effect on the growth of the plants.
Over-chlorinated water can also be detrimental, but you can remove chlorine from the water by allowing the water to sit out for 24 hours before using it.
Avoid getting water on the leaves of an African violet plant as that can lead to spots that cannot be removed.
The fungus Botrytis cinerea is responsible for this blight disease. Initial symptoms include lesions occurring on the leaf’s underside that are small and water-soaked. Often, there’s a fuzzy coating on the leaf, which eventually turns dark brown to gray. The flowers also show similar signs of blight damage. High relative humidity and poor air circulation contribute to the well-being of this fungus. Preventive measures include spacing the plants apart enough so that leaves from other violets do not come in contact with other plants. This fungus spreads by direct contact with a diseased leaf.
Crown or Root Rot
The fungus Pythium ultimum is the cause of crown and root rot, and is generally attributed to over-watering. This fungus infects plants in any stage of growth and causes the leaves to wilt and the crown of the plant and associated roots to become soft, mushy and dark in colour. To prevent this disease, use a pasteurized soil mixture and ensure the container allows for proper drainage. This is a general rule of thumb for most fungal diseases, as they require moist conditions to grow and spread.
Mildew grows in moist, cool climates with poor air circulation. Symptoms include a powdery substance that is light gray in color and shows up on the petioles and stems of the African violet. Powdery mildew reduces the bloom lifespan of an African violet and compromises the entire plant. To prevent this mildew from forming, maintain the violet in a container with good drainage properties and ensure there is an adequate amount of air circulating around the plant.
Petiole rot commonly occurs where the plant stems or leaves come in contact with the pot. The fungus is aggravated by salt accumulation on the rim of the pot. Keep the rim of the pot clean — or cover it with tinfoil to prevent rot. Salt can also be removed from the soil by heavy watering that flushes soluble salts through the pot and out of the soil. (eHow adapted)