'Tis the Season

The holiday season is fast approaching, and many of us have certain traditions which must be observed or it simply wouldn’t seem like the holidays. The Christmas tree is an example of a long-standing tradition while the use of the poinsettia for holiday decoration is a more recent one. Poinsettia (Euphorbia pulcherrrima Willd.) is named in honor of Joel Poinsett, United States Ambassador to Mexico during the early 1800’s. Poinsett, a noted botanist, had heard of a red-flowered plant being used in the nativity processional by Franciscan priests near Taxco, Mexico. Upon visiting Taxco, he found the plant growing wild on the hillsides of the area. He collected some of the plants and sent them to his own greenhouses in South Carolina, and others to botanical gardens and horticulturists.

Poinsettia was first important as a fresh cut flower and was a specialty of Albert Ecke, a German emigrant, who grew cut flowers in southern California around the turn of this century. Upon his death, Albert Ecke’s son, Paul, took over the family business and began the transformation of this species from an outdoor cut flower to that of a greenhouse potted flowering plant. The modern era of poinsettia production began in 1923 with the introduction of a cultivar named ‘Oakleaf’. Many modern cultivars still trace their lineage back to this cultivar and their development to the Ecke family who still maintain a very active breeding program. Poinsettia is the leading potted flowering plant in the U.S. and are available in many unique colors, sizes and plant forms. Many cultivars produced today were introduced to commercial floriculture by the Ecke’s.

Today’s poinsettias have been selected for their outstanding color, free-branching growth habit, early flowering, longevity in the home and bright yellow cyathia that do not abort under poor light conditions. Cyathia are the true flowers of the poinsettia; the colorful appendages to these flowers are actually bracts, not petals. Like any flower, the cyathia will mature and abscise as it ages. This gives the plant the appearance of being old and “past prime.” Poinsettias are short-day plants that bloom only when receiving a critical length of uninterrupted darkness of about 13 hours each day. In the Midwest, this critical daylength is achieved about the 25th of September, which triggers the flowering response. Today’s popular cultivars flower more quickly after sensing short days than did the cultivars of past decades and naturally are in full bloom by Thanksgiving. Therefore, to produce plants at the height of their attractiveness for late sales, conscientious growers delay the bloom of poinsettia by applying night-break lighting.

When selecting a poinsettia for purchase, there are a number of factors to consider. One should select a plant with crisp, healthy foliage and bright bracts. Its cyathia should be tightly clustered and, preferably, just starting to shed pollen. Also, one should avoid plants with insect or disease symptoms. For example, wilted or yellowing leaves often foretell of root diseases. Post-purchase care of poinsettia is extremely important for extended life in the home. A poinsettia should be placed in a brightly lighted location away from cold drafts. Temperatures of 60o F at night and 72o during the day along with high humidity will prolong bract color. Poinsettias suffer when overwatered. One should water only when the surface of the growing medium is dry to the touch. Since poinsettias do not like “wet feet,” be mindful to discard water that might collect in a saucer place under the pot. If the pot containing the plant is foil-covered, be certain there is a drainage hole in the foil.

(Poinsettia photo courtesy of Dr. Bob's Gradening Tips)

Saving your poinsettia and reblooming it the following year is a horticultural challenge. If you are up to the challenge, then take good care of your plant throughout the course of the spring and summer. Next, the plant should be cut back severely (six to eight inches) about Labor Day. Approximately 13 hours of interrupted darkness are needed each day to induce poinsettia to flower. As mentioned, this process starts about September 25 here in Missouri. That regime must be carried out in the home if the plant is to flower, starting on about the same date. Setting your poinsettia in a closet every evening and removing it the following morning is one way to accomplish this task. Once color development is well under way, this “long night” treatment can be discontinued.

Finally, contrary to the belief of some, poinsettias are not poisonous. Extensive testing conducted by Ohio State University resulted in a clean bill of health for the poinsettia. So, enjoy your holidays by including a poinsettia as a part of your decor. You will be just one of millions of Americans who carry on this “new found” tradition.

David Trinklein, Associate Professor, Horticulturalist, UMC (573) 882-9631