An experiment was conducted at the University of New Hampshire, USA, to determine the effect of different air temperatures (averaged over 24 hours) on the weeks required from short days to flowering of poinsettias.  As the main sales period approaches, growers wish to know whether their crop is ahead or behind in flower development.  Experiments show that at 21°C, the crop will need 7-10 days from the end of Short Day treatment to flowering. At 19°C, the period increases to 8-11 days and at 17°C, 9-13 days. Poinsettias grown under natural days often take several days longer than those given Short Day treatment. High night temperatures can also cause delayed flowering. To view the various stages of growth see http://ceinfo.unh.edu/pointset.htm selecting "Poinsettia weekly flower development photos". "GrowerTalks"  Paul Fischer  E-mail: paul.fischer@unh.edu