Q: I have successfully held over three poinsettia plants in a window greenhouse for four years. Every year they get bright red bracts.
Needless to say they are now very leggy. When is a good time to cut them back and how far do I cut them?
A: Keep it in bright light and water only when the soil is dry to the touch. If foil surrounds the pot, remove it and place the pot on a saucer.
Cut off the red bracts in January, leaving only the green leaves. When it is warm enough to set them outside on a shady patio in April, cut the stems back to six inches tall.
As the plants resprout move them gradually to even more sunshine. You may need to move them to larger pots so they don’t wilt on hot days outdoors. Fertilize in April, June and August using houseplant fertilizer.
As they grow bigger, shorten the longest branches a couple of times to make the plants nice and compact.
On October 1 this fall you can start the “fourteen hours of darkness, ten hours of bright light” regimen that will cause them to form colored bracts for the winter holidays once again.