Poinsettia Reblooming - Ask Extension
Regarding your article of January 8, 2016: I have been following the “long night/short day” light exposure protocol you advised and managed to get...
Knowledgebase
Poinsettia Reblooming #607216
Asked November 23, 2019, 1:47 PM EST
Regarding your article of January 8, 2016: I have been following the “long night/short day” light exposure protocol you advised and managed to get my poinsettia from last Christmas to develop several small bright red bracts. I’m unsure of how long to continue the exposure protocol. At what point can I just leave the plant uncovered?
Thank you.
Alpena County Michigan
Expert Response
Well done! Poinsettias can be tricky!
It's been shown that flower initiation depends on length of the photoperiod. Poinsettias require short days to trigger the flowering response.
It's also been shown that the size, as well as the speed, of bract development depends on temperature. Warmer temperatures encourage bract development.
What isn't explained nearly as well is how long poinsettias need to be under short day lighting regimes in order develop large, fully-colored bracts. Some of it definitely depends on the cultivar.
Most culture guides suggest keeping poinsettias under short day conditions until you see pollen present on the first flower (anthesis). There have been cases where poinsettias were subjected to long day lighting after flower initiation but before anthesis -- the immature bracts turned green again.
My recommendation would be to keep it in short day conditions until you see pollen. You should be safe after that. =)
You can also cut back a bit on the fertilizer at this point. Poinsettias don't need as many nutrients in the flowering stage as they do in the vegetative stage.
