Sorry, I can not type chinese now 4 h" _$ ?. d8 W4 l7 _: B / k6 ?7 j4 a8 bBut, I put the poinsettia in a seperate room which should have more than 10hrs black time. Maybe it need more sun light?
at least 10hrs darkness, you can treat it 10~14hrs or longer ,it does not a matter, just a couple of hrs of sun light. and hopefully it can change corlor 3 weeks later till x-mas day.