A Purdue University and University of New Hampshire study, published in the journal HortScience, showed that poinsettia cultivars that initiate and finish in six to eight weeks, are moderate to high vigour, and have naturally large bracts are fine in lower temperatures.
The study showed that poinsettia cultivars finished under cooler temperatures took longer but reached the same quality. They need to be planted a week or two earlier in August to be ready for holiday sales.
Associate professor of horticulture Roberto Lopez said: "Over the past 10 years, energy prices for growers have increased more than 230 percent. As a result, many growers stopped growing poinsettias or lowered their thermostats without knowing what the cultivar-specific consequences would be.
"Now we know that they can save money by reducing finishing temperatures, but they have to plan ahead a little and work with the breeding companies to make sure they are using the correct cultivars."