While it's still officially summer, it's time for home gardeners to begin preparing for the Christmas holidays. Poinsettias which have been saved from previous holidays and grown outdoors through the summer should be brought indoors in mid- September. Poinsettias are short-day plants. Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in the fall. In order for poinsettias to flower for Christmas, they must receive complete darkness from 5 p.m. to 8 a.m. each day from early October until the bracts show good color, usually around early December. (Most poinsettia varieties require 8 to 10 weeks of short days to flower.) Gardeners can protect their plants from light by placing them in a closet or by covering with a cardboard box. When using cardboard boxes, cover any openings to insure complete darkness. Exposure to any type of light between 5 p.m. and 8 a.m. will delay or possibly prevent flowering. During the remainder of the day, the poinsettias should be placed in a sunny south window. Keep the plants well-watered and fertilize every 2 weeks during the forcing period. While poinsettias are difficult to flower in homes, proper care can reward home gardeners with a colorful plant for the holiday season.
This article originally appeared in the September 14, 2001 issue, p. 1090.