Flower Power: Ten Fun Facts About Poinsettias

Students grow seventeen poinsettia cultivars at CSU.
Students grow seventeen poinsettia cultivars at CSU. Colorado State University
Poinsettias, with their bright-red leaves and star-like shape, are a staple in Christmas decorating, and also the subject of much study at Colorado State University.

Upper-level students in CSU's College of Agricultural Sciences’ Department of Horticulture and Landscape Architecture have a chance to apply classroom knowledge at the Horticulture Center greenhouse. The hands-on experience is part of a practicum class taught by Assistant Professor of Controlled Environment Horticulture Joshua K. Craver. Each student was assigned upwards of a hundred plants to oversee, with a goal of selling them at the school's annual poinsettia sale in early December.

“We’ve been growing these plants since July,” Craver says. “It’s been a long time in the greenhouse, and we finally have these plants ready to hit the door."

Before parting with the plants, Craver shared ten fun facts about poinsettias — and gave insight on how to keep them flowering for years to come.

Poinsettias are native to Central America
Poinsettias naturally grow in Central America and are most concentrated in an area of southern Mexico. In their native tropical environment, they can grow up to fifteen feet tall.

It’s said that the poinsettia's association with the holidays stems from Mexican folklore. According to legend, a young girl lacked means for a gift to present during Christmas Eve services. She created a humble bouquet of roadside weeds, but upon placing it on the church altar, they became vibrant red flowers.

The name “poinsettia” came from Joel Roberts Poinsett
Poinsettias were brought to the United States in 1825 by Joel R. Poinsett. "He was the first appointed U.S. Ambassador to Mexico,” explains Craver, who notes that “the common name of poinsettia was given in 1833 in honor of Poinsett.”

Poinsett is also remembered by Poinsettia Day, traditionally celebrated on December 12, the day of his death in 1851.

The Ecke Family made poinsettias a holiday staple in the U.S.
The Ecke family consisted of German vegetarian immigrants who moved to Los Angeles in the early 1900s and began selling poinsettias, later naming it "the Christmas flower."

“This was not a commercial crop for the U.S. until the 1900s,” Craver says. “You’ll often see the Ecke family associated with poinsettias and poinsettia production. It was Paul Ecke Sr. who, in the 1920s, began growing poinsettias as a cut flower in Hollywood and Beverly Hills. But it wasn’t until the 1960s that his son, Paul Ecke Jr., started to promote poinsettias as this holiday potted crop.”

Decades of breeding resulted in a variety of cultivars
With Paul Ecke Jr.’s promotional efforts, “a lot of breeding efforts started to happen,” explained Craver. “You see the natural poinsettia in its habitat, but what we grow now is, in many cases, nothing close to that.” It’s still the same species, “but we’ve bred for so many different attributes. Those attributes range from when those poinsettias will actually go into flower to the color of the bracts.”
Red poinsettia bracts differ from the yellow cyathia flowers, found at the center of the leaves.
Unsplash / Robert Woeger
Poinsettias are known for their bracts, or leaves — not their flowers
“Bracts are these modified leaves around cyathia flowers,” says Craver. “We associate them with flowers, but [poinsettia] flowers are at the center of the sets of bracts. Called cyathia, they’re these little yellow flowers where the pollen is produced.”

But the bracts are what we associate with the color of poinsettias. “Bracts can be red, multi-colored, pink, orange, white — there’s so many colors of bracts that can be developed through breeding,” he notes. At Colorado State University’s poinsettia sale, seventeen different cultivars will be available for purchase.

Poinsettias are highly sensitive to light
Light exposure is “one of the most fascinating and frustrating pieces of poinsettia production,” laughs Craver. “Poinsettias are what we refer to as a ‘short day’ plant, so they’re naturally going to go into flower when we have short days and long nights.” Given the season’s natural light cycle, he adds, “it makes sense why this makes such a perfect holiday crop.”

But he points out a key issue: “That flowering response only takes a really small amount of light to trigger. If somebody walks [into the Horticulture Center] in the middle of the night and accidentally turns on an overhead lamp, that’s going to trick those plants into thinking — oh, no, it’s not actually a short day.”

Craver shares that even street lamps bleeding into the greenhouse have prevented plants from flowering; he’s heard reports that car headlights driving by greenhouses have caused the same problem. “If you don’t get these short days and long nights, you’re going to have a bunch of green poinsettias come December, because those plants never actually started the process of flowering,” he warns.

Poinsettias’ vibrant colors can last for several weeks
“When you get these plants at home, the flowering is done. We’ve done all that work for you to make sure that they go into flower and produce that color,” explains Craver. “You’ll have color through the holiday season and likely see that color continue into January, at least.”

You can make your poinsettias reflower
“If you’re wanting to hold those plants over until the following year, eventually you’re going to need to go in and cut off those flowers. Pinch those plants back, and they’ll develop new flowers for the next year,” shares Craver. During this vegetative growth stage, you’ll also want to prune, water, fertilize and perhaps re-pot.

“We have lots of reports of people who previously purchased plants from our sale," he continues. "Around September/October, they start to put their plant into a closet at night and shut the door. They’ll put them out in the morning, and if they do that consecutively over the course of a month and a half or so, they’ll be able to trick their plant into flowering again.”

Poinsettias are not poisonous to pets or people
Poinsettias produce latex. "When you pinch the plant, for example, you’re going to see that white latex come up to the surface of the stem,” explains Craver. So if you have a latex allergy, maybe don’t go squeezing your poinsettia. Otherwise, though, they're not poisonous.

“Unless you have a cat that’s going to eat an entire poinsettia plant, you may have some issues there," he adds. "But if a leaf were to be consumed, that being fatal is pretty well established as a myth. Poinsettias are not of any more concern than any other normal houseplant.”

Poinsettias are the country’s best-selling potted plant
Despite its short season of availability, poinsettias are the best-selling potted plant in the United States. According to the University of Florida, “Every year, more than 70 million poinsettias are sold within a six-week period at a nationwide value of more than $250 million.”
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