Assuming your poinsettia has survived the holiday rigours, continue to keep it in a bright spot away from drafts and heaters, giving it moderate water and a monthly feed of an all-purpose houseplant fertilizer.
Poinsettias like warm days (18° to 21°C) and cool nights (13° to 18°C). Remove leaves and “flowers” (they are actually colourful bracts) as they fade. In late March or April, cut the stems back to about 15 centimetres and reduce watering to give the plant a resting period. In late May, pot it up to a larger container with fresh soil.
In mid-June, put it outside in dappled shade. Keep watering and feeding and, in July and August, pinch back the branches to encourage bushier growth. You could plant it in the ground, admire its foliage till frost and say adieu. Or leave it in its pot and bring it indoors around Labour Day, spraying with insecticidal soap if any pests are present.
Starting October 1, give it at least six hours of bright light and 14 hours a day of uninterrupted darkness—even a street light can affect bud set/colouration so put a cardboard box over the plant inside a closet. Continue for eight to 10 weeks until small bracts appear, then keep it in its sunny, draft-free spot. By Christmas, it should be resplendent once again.
Image by istock/lillisphotography