Wax begonias are almost exclusively F1 hybrids produced by large nurseries in huge quantities. These plants will not produce accurately from seed, but like many other begonias, they propagate easily from leaf-tip cuttings. Take cuttings without blooms but at least two nodes and bury them in the moist potting soil mix, then leave in a warm, semi-shaded spot until new growth appears. The best time to take cuttings is in the spring when the plants begin to grow again.Wax begonias happily grow into small shrubs if allowed to, reaching a maximum height of about 18 inches, depending on the cultivar and species. Like other begonias, they thrive when they are slightly pot-bound, so it's likely that a wax begonia will only need to be repotted once or perhaps twice in its life. In most cases, it's better to take cuttings of older plants than to struggle with repotting and rehabilitating leggy specimens. If you are repotting, do it in the spring into a slightly larger pot with fresh, fast-draining, and richly organic potting soil.