African violets are such an easy-care plant that in tending them, the "dont's" far outweigh the "dos"! Don't move them, don't water them too much, don't fertilize too often, and don't repot them until they overflow their pots!
Although African violets do like evenly moist soil, letting the soil become waterlogged is certain death for the Saintpaulis. Overly saturated soil takes up the air-space African violets need to thrive. Since like many plants, the African violet both breaths and drinks through it roots, roots left standing in water deprive the plant of air and the Saintpaulis drowns.
There is some disagreement on how to water an African violet. Some growers prefer watering from the top. When watering African violets from above, take special care to keep leaves dry. Water left standing on leaves results in dark spots and rings that are unattractive and shorten the lifespan of the leaf. Many growers prefer to let the plant drink from a saucer or attached plant tray. Still, another method of watering is the wick system. Wick systems and two-part pots give your plants the water they need without leaving them with wet feet or splashing leaves with water.
All three types of watering are admissible as long as you don't get water on the leaves of the plant and water when the soil is about 50% dry or feels dry to your touch.
Don't use soft water. Tepid tap water or bottled water works fine. Although some African violet growers use distilled water, along with contaminants like chlorine, distilled water is also devoid of minerals and other nutrients that help your African violet grow.
If you use tap water, let it sit overnight so that it's room temperature at watering time. In addition, letting water sit helps to evaporate fluoride and chlorine, two of the harmful chemicals your African violet doesn't need.
Over-fertilizing your African violet can result in as much harm as over-watering your plant. Over-fertilizing can cause leaves to become brittle and crack; it may also produce lesions on leaves and stems and it can curtail your African violet's ability to absorb beneficial elements, which results in wilting, leaf tip burning, and a decrease in bloom.
African violets like to be pot-bound. The less you have to replant them, the happier they are. However, in container gardening, nutrients are depleted quickly and need to be replenished either by repotting with fresh, nutrient rich potting mixture or by adding nourishment (fertilizer) to the pot.
Use only a fertilizer specifically formulated for African violets. The Saintpaulis requires certain trace elements which aren't available with an all purpose food, as well as a soil acidifier. African violet food takes care of these needs. A good African violet food is balanced with equal amounts of the primary nutrients, nitrogen (N), phosphorus (P) and potassium (K), usually in a 10-10-10 formula. Your African violet food should also be 100% water-soluble so that your plant can absorb the fertilizer's beneficial elements.
However, be sure that your African violet food won't prove toxic to your Saintpaulis. Although labeled for African violets, many fertilizers contain impurities that are harmful to the Saintpaulis. One component often found in fertilizers is urea, which is a source of nitrogen. Although it's cheaper than other sources of nitrogen, urea causes root burn on African violets, which reduces your plants ability to absorb water and beneficial nutrients.