Poinsettia – Forcing into Color
Q: I still have my poinsettia from last Christmas. Its leaves are all green now. People have said to put it in a dark closet, so it will look good for this Christmas. Should I do that? Any suggestions?
A: If you want to make it change color in time for the holidays you should start on October 1 putting it in complete darkness for fourteen hours each day.
Most folks use a big cardboard box for this purpose. The other ten hours of its daily life should be spent in bright light. The goal is to trick the plant into forming bloom buds, which will lead to colorful bract (modified leaf) formation.
Fertilize every two weeks and follow the 14/10 regimen until early December. By that time you should see the foliage color you anticipate.