I have a dracaena marginata in my office that has done very well for about six months. watering instructions were to keep the soil generally most, which I have done, and for a long time the plant was perfectly green. The problem is that when I have been out of the office for periods of 1-3 weeks, and I leave the plant in the care of others. After each trip, some of the plant's leaf tips have turned brown. Recently, however, I returned after 10 days to more brown than ever before. One complicating factor: I have never fertilized the plant. So now I wonder: Yes, I need to water it again, but should I fertilize now that winter is approaching?