It is quite possible to get your poinsettia to bloom again next season. Difficult but possible.
Poinsettia continue to bloom through January and February if cared for properly. If your plant looks nice, then you are doing a wonderful job of caring for it. Proper watering is the most important element with a nice bright location away from cold drafts and hot temperatures.
By March or early April, your poinsettia may start to look a little ragged and probably has lost quite a few leaves. It is time to cut the plant back to a height of about 4 to 6 inches. Continue to water in the same manner as before and start to fertilize using a 20-20-20 balanced fetilizer every 3 to 4 weeks.
The poinsettia should be re-potted about May or early June. Move the plant to a pot that is 2 to 3 inches larger in diameter with drain holes. Add any good soil less mix of potting material and start to expose the plant to sunlight. Do this slowly in order not to sun burn the plant and continue to water properly. The pot should be rotated once or twice a week to encourage symetrical growth. New shoots will soon appear and these should be pinched off about a quarter of inch to promote branching. Fertilization and pinching can be performed at the same time about every three weeks.
Move the poinsettia to the garden in June after the danger of frost is past. The pot can be buried in the garden soil. Choose a location that is sunny with light shade in the afternoon. You may need to move the plant slowly into more sunshine for a few days to allow it to grow accustomed to the stronger hotter sunlight.
Now here is the key to getting the poinsettia to bloom for Christmas. You should move the plant from the garden back indoors in early Sepember. You want the plant to be exposed to about six hours of direct light. The balance of the 24 hour cycle should be dark. This is often most easily accomplished by using a bright location during the day and then moving the plant to a dark room for the night. That room should have basically no light…..close the shades. Even a street light shining in the window may cause the plant to refuse to initiate color change.
Poinsettia flowering is photoperiodcally induced which means that flowering begins when the nights are long enough. The plant should have 12 to 14 hours of strong darkness and 10 to 12 hours of daylight with 4 to 6 hours of good light with sun from October 1 to mid December. The dark period is the most important.
The upper bracts should begin to show color in November and after that begins the light guidelines are less important.
There you are…………your poinsettia should be very colorful in time for Christmas. Now you will agree that the above is fairly arduous process and you may think it is easier to just buy a new plant. But at least, you now know what poinsettia growers have to do to get their crop ready for the Christmas market. The same principles and processes apply for one plant at home or 10,000 plants in a greenhouse.