Poinsettias are Mexican wild flowers grown for their vivid red, pink, white and multicolored floral bracts that are at the height of their beauty during the Christmas season. Although their brilliant leaf like bracts are the best feature of the poinsettias and are called flowers, they are not true flowers, the real blossoms, tiny and rarely noticed, rest in the center of the colored bracts.
Many people ask how to make poinsettia blossom in the home. The theory is easy, but the job to do this is tedious.
Poinsettias blossom only when the hours of darkness are longer than the hours of daylight. Normally, poinsettias begin the process of flower-bud initiation during the period between mid September and the first week of October as the days short getting shorter.
This is the key to having flowers at Christmas-time.
The plants need 9 to 10 hours of light daily and 14 to 15 hours of darkness. This should guarantee flowers, provided you can maintain a temperature of about 65 degrees and the right amount of light and darkness needed.
They must never have artificial light, even for a moment, during those periods of darkness. Shading is not sufficient: they need absolute darkness.
You can put your plant in a closet, cover with a light-tight box or a black plastic bag, or in a room where no light will be, no matter what.
It's a good idea to set up a daily schedule, cover your plant at say, 5 PM and uncover it at around 7 AM, or even 8AM. This is quite a regimen, but it works.
Another thing it does too, you'll get a higher regard for the professional who grow handsome poinsettias in full bloom at Christmas time.