If your lucky bamboo is healthy, you'll notice that it quickly outgrows its original shape. Instead of maintaining the nice, twisted corkscrews or interlocking patterns, the new shoots tend to grow straight up. Attractive at first, they will quickly result in an unbalanced plant. Fortunately, lucky bamboo is easily propagated.
Taking cuttings. The first step is to take a healthy cutting. I usually take cuttings after I've trimmed the mother plant. Make sure the cuttings have at least one leaf joint, and preferably more. Trim excess leaves away to expose the growth node. Lucky bamboo can be rooted bare, or you can use a rooting hormone. Under normal circumstances, rooting hormone shouldn't be necessary because the plant readily roots. However, if you have several failed attempts, a rooting hormone might increase your chances.
Rooting lucky bamboo in water. This is the preferred method. Take trimmings that include at least one leaf joint and put them into distilled water. New, slightly reddish roots should emerge from the bottom of the stalk. Keep the water clean. Once the roots have emerged, you can either put the plant in a vase with decorative pebbles or pot it up in regular soil.
Rooting lucky bamboo in soil. Lucky bamboo will also readily root in soil. To root a new plant, gently push the trimmed stalk down into fresh potting soil, making sure that at least one root node is beneath the soil level. Keep the plant moist and warm until new growth begins to emerge.
When rooting lucky bamboo, however, remember that the new plant will not have the same distinctive stalks and growth habit of the parent. It'll still be a pretty and resilient houseplant, with narrow green leaves and straight stems, but it won't look like a professionally shaped and grown lucky bamboo.