Although stem plants are relatively tolerant of trimming, the lower stems near the root become old and new shoots do not develop easily with repeated trimming. When this happens, I add a fertilizer containing some plant hormone to encourage the development of new shoots. If the stems become overly aged and the base of the plant lifts up from the substrate, I pull out the entire stem plant, trim off the older bottom section, and replant the top younger sections of the stems. You can enjoy stem plants over a long period of time through trimming and rejuvenating in this manner.