While you may be able to rule out the possibility of too much sun, the complexity of plant nutrition makes it difficult to definitively diagnose Nitrogen Overload. Due to the complex interaction between plant nutrients, it is often very difficult to pinpoint the precise element causing problems. Short of sending your plant to a laboratory for testing, you will probably have to be satisfied with simply knowing that your African Violet suffers a nutritional imbalance without knowing the exact elements involved. This said, do not be discouraged. This is called Leaf Tip Burn, and it is brown in color.
Flowers drop off .
Plant growth is slow . After eliminating the possibility of too much sun, drench the soil and let any excess water drain from the bottom of the pot. Wait one week before fertilizing again. For Miniature Violets, you should use a fertilizer that contains about half that amount, i.e., about 7 percent nitrogen. If this does not work, either reduce the amount of fertilizer that your African Violet gets or reduce the frequency of applications.