Keep, don't toss, your poinsettia after the holidays.
On Jan 1, use an all-purpose house plant fertilizer, and continue light, water and fertilizer to keep plant colorful for many weeks.
In March, remove faded and dried parts of the plant, top-dressing the plant with fresh soil, using a commercially available sterile mix.
In late May, the plant could be three-feet high. Cut back all stems and branches half their length to promote side branching. Repot in a larger container and move the plant outside, first to indirect, then direct light.
Trim the plant again on Independence Day to promote more side branching. Make sure the plant is receiving enough sunlight and slightly increase the amount of fertilizer.
Around Labor Day, your plant may have grown to four or five-feet high. Move the plant indoors to a place where it will have six hours of direct light from a curtain-free window.
On the first day of fall, give your plant 14 hours of uninterrupted darkness, either in an unused closet, the basement or under a box, and 10 hours of bright light each day. Keep night temperature in the low 60s. Continue to water and fertilize. Rotate the plant each day to give all sides even light.
Around Thanksgiving, discontinue short day/long night treatment. Place the plant in a sunny area with at least six hours of direct light. Reduce water and fertilizer.
By the time the Christmas holiday season rolls around, if you're lucky, there should be buds and blooms on your poinsettia.