Poinsettias do best with temperatures between 65- and 75-degrees F. Consistency is key so avoid drafts from windows, or heat sources such as the fireplace or space heaters. Bright, indirect light is preferred but keep the leaves from touching cold windows.
Soil should be kept moist. If it dries completely, the poinsettia will wilt and potentially lose some leaves. Water the plant in the sink until water runs through the drainage holes of the container. If the poinsettia is left in standing water such as in a saucer or in the plastic sleeve they are often sold in, the roots will rot.
Fertilizing and other maintenance is not necessary until after the holidays. (Cynthia Domenghini)