By HOLLY RAMER
DURHAM, N.H. (AP) -- The 700 red poinsettias lined up in a University of New Hampshire greenhouse are sort of the horticultural version of hybrid cars: they're being grown at different temperatures in hopes of creating a more fuel-efficient plant.
Growing the perfect poinsettia has always been tricky. There's a narrow window to get plants to the ideal size, shape and color in time for the Christmas season. In recent years, high fuel costs -- for heating greenhouses and shipping plants -- have also made the work more expensive.
With that in mind, researchers like those at UNH have been experimenting with "cold finish" techniques that would allow growers to drop the temperatures in their greenhouses and save on heating costs.
Though cooler temperatures slow plant growth and can require earlier planting, growers who cut back a few degrees late in the season still could save 20 to 40 percent on energy costs, depending on their location, said Roberto Lopez, an assistant professor and floriculture extension specialist at Purdue University in Indiana.
"We've done the math ... even if you have to start the crop a week early, or even two weeks, you still end up saving significant amounts," he said.
And some of the varieties tested this year apparently don't need the earlier start, said Brian Krug, UNH Cooperative Extension specialist.
For example, he said, a grower using natural gas to heat a 1/2-acre glass greenhouse in Toledo, Ohio, would spend about $18,200 to grow about 11,800 plants at the conventional temperature of 71 degrees versus $13,500 if the temperature were dropped 9 degrees late in the season. A comparable greenhouse in New Hampshire, where oil heat is more common, would save about $7,300 off its $33,100 heating bill.
Poinsettias, a subtropical species native to Mexico and brought to the United States in the 1820s, are the nation's most popular potted flowering plants, according to the U.S. Department of Agriculture, which puts the wholesale value of last year's crop at $154 million, 5 percent lower than 2007. This year's estimates were not available.
The poinsettia market is dominated by a handful of companies that sell cuttings to growers ranging from mom-and-pop greenhouses to large industrial operations. The average wholesale price for plants in 5-inch pots or larger was $4.82 last year, USDA said. Retail prices can be as high as $40.
Besides cold finish research, Purdue -- along with North Carolina State University and the University of Florida -- participates in the National Poinsettia Cultivar Trials to test new varieties. UNH and other schools also conduct smaller-scale trials and hold open houses for public input. At UNH, that happens Thursday through Saturday. Purdue's open house is Sunday.
Lopez, who's been researching with UNH for two years, said many poinsettia varieties don't make the cut.
"There are some that if you try to cold finish them, they won't be ready until Valentine's Day because of the delay in development, or you end up with really unattractive plants that are too small, or the bracts are too small," he said. Bracts are the colored leaves resembling flower petals on a poinsettia.
At the UNH research greenhouse, about 10 poinsettia varieties were started from cuttings in August at the traditional nighttime temperature and then moved to a variety of lower nighttime temperatures October. Researchers use infrared temperature sensors, photographs of specific bracts, careful measurements and computer software to analyze the plants' growth and development.
Even though fuel prices have dropped nationally this season, the research is still critical, said Andy Higgins, president of California-based Ecke Ranch, one of the world's largest poinsettia breeders and producers. This August, natural gas prices were at a seven-year low, down 80 percent from the previous summer. Heating oil prices were half of last year's.
"The length of time it takes to produce a new poinsettia (variety) is a minimum of five years. So it's great energy prices went down, but we see it as very temporary," he said.
Last year's high fuel prices prompted many growers to scale back their orders for cuttings dramatically. This year, growers are being conservative, not because of fuel prices but because of the generally weak economy, said Higgins, who expects a reasonably good season.
The Society of American Florists says surveys show nearly three-quarters of poinsettias sold each year are the traditional red, but there also are white, pink and orange varieties with names such as Polar Bear, Ice Punch, Orange Spice and Peppermint Twist. Some newer varieties feature curled leaves resembling rose petals.
David Goudreault, assistant manager of the UNH research greenhouse, said he is more likely to judge a plant by stem strength than color, though he is partial to the "Ice Punch" variety, with rosy red bracts lightly washed with white over their centers.
"I have a hard time making up my mind," he said.
Copyright 2009 The Associated Press.