Poinsettias do not like to dry out. Try to keep the soil moderately damp to the touch at all times. Plants getting lots of light and/or kept in a warm location will need more frequent watering than those in low light, cool locations. Check your poinsettia at least twice per week to make sure it does not dry out. Poinsettias are sensitive to temperatures below 65 degrees. So avoid cold, drafty window sills.  Close proximity to heat sources will cause poinsettias to dry out too quickly. Comfortable temperatures are good for poinsettias.

         When the flowers fade and the plant no longer looks attractive, do the following: Cut the stems back to just above the point where new (green) growth is emerging. This usually means cutting off one-half to two-thirds of the stems. It may look ugly until the new growth has filled out in a few weeks. Move the poinsettia to a sunny windowsill. Do not repot the poinsettia. Water and fertilize the poinsettia regularly. Do not let it get dried out. Avoid temperature extremes and cold drafts.

Rebloom a poinsettia:

          Beginning in late September, you must provide your poinsettia with 12 hours of complete darkness each night and 12 hours of good light during the day. For about eight weeks, you will have to move your poinsettia to a dark closet every night and back to the windowsill each day.