poinsettia plants still green
I have had my poinsettia plants covered for more than 12 hours and they still are green. How long do you keep them covered before the plant turns red? I am trying to get my poinsettia plant to turn red for Christmas. What do I do next?
The link has good info, and since you don't say how long you've been doing the 12-hour-darkness thing, maybe you just need to keep it up. But you might want to be aware that they don't always rebloom, no matter what you do. If this one doesn't work, keep trying.
This link will take you to a very informative, detailed article on 'reblooming' poinsettias: https://www.gardeningknowhow.com/ornamental/flowers/poinsettia/how-to-make-poinsettia-turn-red-make-a-poinsettia-rebloom.htm