Once Christmas is over, poinsettias can be repotted and placed outdoors in a sunny location or kept indoors as a houseplant. If kept indoors, poinsettias will need regular watering and fertilizing to maintain their health and beauty. To keep them looking vibrant after the holidays, place them in a sunny window or use a grow light to provide the necessary light. You can also cut them back to encourage more growth in the spring, and they can be propagated by cutting off a stem and rooting it in water or soil.