By Jodi Tooke
Now that Thanksgiving is over, we’ll all be tempted by the glorious red Poinsettias in stores and nurseries. Poinsettias were named in honor of Joel Roberts Poinsett, who introduced them to the United States in 1828.
A botanist and physician, Poinsett was also the first United States Ambassador to Mexico. Discovering the plant in Southern Mexico, Poinsett sent cuttings to his home in Charleston, South Carolina. It has been cultivated as a greenhouse crop since just after the Civil War, and today there are over 100 varieties.
In nature, Poinsettia (Euphorbia pulcherrima) is a perennial flowering shrub once considered a weed. They may reach 15 feet with fiery red blooms which appear naturally in December.
Although they look like flowers, the “blooms” are actually colored bracts (modified leaves). In the center of the colorful bracts are little yellow flowers, or cyathia. The plant drops its bracts and leaves soon after those flowers shed their pollen, so choose plants with little or no yellow pollen showing for the longest-lasting Poinsettias.
Poinsettias can be encouraged to “rebloom.” The colors of the bracts happen through photoperiodism, meaning that they require darkness (12 hours at a time for at least five days in a row) to change color. At the same time, the plants require abundant light during the day for the brightest color. Any incidental light during these nights hampers colored bract production.
Outside its natural environment, Poinsettias thrive indoors in temperatures ranging from 65 to 75 °F, where they prefer good morning sun. Water when the soil surface feels dry to touch. Flowering Poinsettias may be kept outside, even during winter, as long as they are kept frost-free.
Jodi Tooke volunteers with GC Master Gardeners of the UofA Div. of Agriculture, Cooperative Ext. Service. Master Gardeners pool skills and resources to improve home horticulture, stimulate interest in plants and gardening, and encourage beautification. For more info: 501-623-6841 or abates@uaex.edu.
