FAIRBANKS, Alaska — Poinsettias are in bloom at the University of Alaska Fairbanks this week, which is a bigger accomplishment than many might suspect.
Growing the Mexican holiday flower in the depths of an Alaska winter is an annual triumph for students at UAF, who nurture it from a nondescript green houseplant to a colorful centerpiece during the fall semester.
UAF horticulture professor Meriam Karlsson grew at least 200 of the plants this year with students in her Introduction to Plant Science class. The annual project, which has been under way for at least the past decade, is more than just a holiday ritual.
So much research has been done on poinsettias that their maximum day length has been figured down to the minute. Past 12 hours and 20 minutes, poinsettias generally won't produce the colorful leaves that have become a symbol of the holiday season.
Because of that, the project is a clear lesson in the role that light can play in plant growth during a dark winter.
"If they didn't believe in photo period before, they do now," Karlsson said of her students.
Two rooms of poinsettias at Arctic Health Research Greenhouse are surrounded with black curtains to rigidly control the amount of light they get, with dozens of high-pressure sodium bulbs overhead to offer simulated sunlight. Any glitch in the process — perhaps even headlights shining from the nearby parking lot at the wrong time — can ruin their ability to change color, she said.
In that case, the plants look like a healthy but ordinary plant — it's the leaves that produce the bright red or white colors, not its flowers. Contrary to popular myth, the plants aren't poisonous, unlike other holiday staples like holly, mistletoe and lilies.
Poinsettias have a reputation as fragile plants, and plenty of owners unintentionally kill theirs after the holidays. But Karlsson said poinsettias can survive year-round with a little effort, although their light needs to be closely watched in the fall to let their leaves change color.
"The real reason poinsettias die is because people put them in their house at Christmas and go to Hawaii for two weeks," said Cameron Willingham, a research professional at the greenhouse.
Many of the poinsettias grown at UAF are distributed around the Fairbanks campus, with others maintained at the greenhouse for students to study next winter. The plants, which are the only poinsettias grown in large numbers in Fairbanks, aren't sold to the public.
Karlsson said this year's crop is looking especially good, and gives much of the credit to the new year-old greenhouse facility on UAF's upper campus, which is hosting its first poinsettia crop. She said better climate controls are helpful to the plants.
"It's really difficult to grow them in Alaska because of the light and heat," Karlsson said. "We probably have the best poinsettias we've had in the last 10 years."