Christmas cactus plants enjoy bright light, but too much direct sunlight can harm them. Keep your plant in a sunny window facing east, if possible, to prevent it from sitting in direct sunlight all day. During the summer months, you can move your Christmas cactus outside, but be sure to keep it in a shaded area and continue watering and fertilizing it as if it were still inside. In the winter months, the Christmas cactus should move indoors and get between four and six hours of indirect sunlight.