Cut any leaves that are distorted or afflicted with insects or disease, such as cyclamen mites or powdery mildew. Cut the leaf and stem, just above the crown where it is attached. Use a pair of clean scissors or hand clippers, or snap them off with your fingers.
Cut off the leaves at the base to thin the plant. Thinning African violets increases light and air flow to help dry out the leaves and soil. This prevents some diseases, such as Botrytis blight and crown rot, that spread readily under moist conditions. Thin one out of every three or four leaves in such a way that the remaining leaves are evenly spaced and the plant is still attractive.
Cut off a healthy, mature leaf and approximately 1 to 2 inches of its stem or stalk. Use a sharp pair of scissors or clippers. Plant the stalk in perlite or potting soil to propagate another African violet. In general, it takes six to nine months for the leaf to develop into a flowering African violet plant.