Answer: African violet cuttings take about a month or so to grow. While new plants can be done by starting them in water, it is more often done using soil instead. Here are instructions from the African Violet Society of America on how to do that.
While the water method can be used, the following method may provide better results. Rooting African violet leaf cuttings 1.) Choose a leaf that is fresh and fairly young but full size. Healthy vigorous leaves will root quickly rather than rotting. 2.) Cut the stem at an angle, leaving a stem below the leaves that is 1 - 2 inches long. 3.) Fill a small pot (that has drainage holes) with a very light potting mix. A mix of half vermiculite and half potting mix will work well. 4.) Set the leaf into the prepared pot at an angle. Do not set it into the soil very deeply. Water and allow the excess moisture to drain away. 5.) Place the potted leaf into a clear plastic bag (zip-loc bags work well) and seal it tightly closed. You may wish to blow into the bag as it is sealed to puff it up with air. 6.) Set the leaf in a bright location out of direct sunlight. It normally takes about one month for the leaf to root and another month for the plantlets to appear. The clump of plants that develop will need to be divided when the leaves are about the size of a dime. Dividing a leaf clump 1.) Remove the leaf clump from the pot, and lay on a work area. 2.) Gently work the soil away from the roots until the small plants can be separated. Usually they will fall away from one another as the soil is removed. Look for each plant to have a small rosette of leaves, often attached to a main stem, with some roots at the bottom. Leaves often produce 5 or more plantlets. 3.) Prepare a small pot (2" diameter, such as a Solo plastic bathroom cup with a hole poked in the bottom) for each small plant. Fill the pot with very light potting mix that has been premoistened. If you mix your own (recommended), use one part peat moss, one part vermiculite, and one part perlite. Do not pack the soil down! 4.) Make a small indentation in the surface of the potting mix using a pencil or a finger. Set the plant into the indentation and gently move the potting mix to stabilize the plant. 5.) Water and allow the excess to drain away. Set the young plants inside a clear plastic bag or plastic container and seal tightly closed once again. Set in a bright location away from direct sunlight. 6.) In about a month, the plants will be well rooted and beginning to show mature growth. Open the container gradually over a period of two days to allow the plant to adapt to lower humidity. After this transitional period, your violet may be set in any bright location and watered on a regular schedule.
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