It started in October, a little later than normal this year. The 2016 poinsettia began its journey to red for 2017. The poinsettia holiday blooms are not really blooms but red leaves and flower bracts.
This one was purchased last Christmas and was not repotted.
The color change began a little late this year. It begins when the leaf petioles begin turning red. After seeing this, we expect the red coloring to continue moving up to the leaves to change them, but that's not how the process works.
After the petioles, the new leaves that are not yet fully grown begin changing. A little chartreuse at first, then a little light beige, then some red tinge begin to appear in them as they continue to mature.
At this time, I give it some regular low doses of nitrogen fertilizer. I want those leaves to grow big, since they will be the red 'petals'.
The light green leaves have matured. All new leaves the plant produces are now solid red. Over time, these mature into the poinsettia in time for the holiday.
The journey to red is not easy. It means coming home from work, fumbling in the dark to find the plant on the east window, taking it to the basement in the dark and putting it to bed until the next morning. Darkness for 12-14 hours is necessary in order for the poinsettia to bloom again.
Somewhat smallish blooms this winter are telling me to repot the plant for next year's holiday season.