One of the visual clues that the winter holidays are at hand is the sudden appearance of brightly colored poinsettias in just about every floral display you come across.

They make their regular appearance about this time every year at the Fresno State Floral Laboratory, produced by students and available to the community.

Fresno State horticulture students have grown poinsettias for more than 15 years as part of a crop project their senior year, said Calliope Correia, the nursery technician at Fresno State. She said poinsettias can be difficult to cultivate because they’re sensitive to temperature and require high maintenance, including fertilizer, insecticide, and fungicide.

They also are sensitive to the amount of daylight they receive. Getting the plants to change into a brilliant shade of red requires a period with sufficient darkness. “We used to have to cover them with black cloth, but the new varieties turn on their own,” Correia says. “If we left the lights on, however, they may not turn color in time for the holidays.”

The plants start out in August as rooted cuttings, about two to three inches high. “You want them to be true to the variety,” Correia says. “Growing them from seeds can be a gamble as to what is produced.”

For the most part, poinsettias have red, pink or white bracts (specialized leaves). A few, however, are red and white, called Sparklers. The flower part of the plant is yellow.

Correia said poinsettias, which are native to Mexico and Central America, can reach up to eight feet if they are “really happy” and they’re not as dangerous as some people think.

“While they do have an irritant in their sap that can make you itch, if your pet eats a leaf or two, the most that will probably happen is a bad stomach ache, which can happen from eating a lot of other plants, too,” said Correia. “So it’s a good idea to keep all houseplants out of the reach of pets.”

Growing poinsettias teaches students propagation skills, such as irrigation and temperature control, which are useful in commercial and greenhouse growing. Marketable poinsettias are dressed in gold or red foil and usually sold wholesale to local retailers and at the Rue and Gwen Gibson Farm Market on campus.

Started in the early 1970s, the Floral Lab employs nine students who design and market arrangements for banquets, parties, holiday events, funeral services and weddings. It is located at 3150 E. Barstow Ave., east of Chestnut Avenue.

For more information, contact Elisa Valdez at 559.278.7627 or or Correia at 559.278.2952 or

(Text by April Schulthies, the Office of Communications catalog editor.)

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