Ti plants are tropical foliage that love warm weather and lots of water in the summer. There are all types of Cordyline plants and there are many different varieties. Is your plant grown outdoors or as a houseplant? Do you live in a tropical climate? Do the leaves die from the tips or do they turn yellow from the center first? Is it only the oldest leaves or new growth as well? If you have a houseplant, grow it in bright light near a sunny window. Make sure the container has a drainage hole. In winter, when the days are shorter, cut back on watering as the plant will want to go dormant. Send me a photo of the plant and I will be better able to diagnose the problem. Keep growing, Marianne Binetti