10 November 2005
Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580 fax: 434.872.4578
Poinsettias (Euphorbia pulchenima) are native to southern Mexico and Guatemala where they grow as a large shrub or small tree. They first were brought to the United States in 1825 by Joel Poinsett (hence the common name) who was our first ambassador to Mexico. In the early 20th century, the Ecke family of southern California became associated with the outdoor production of poinsettias for use as a landscape plant and as a cut flower.
Since that time, the Ecke name has become synonymous with poinsettias in the greenhouse industry. Almost all plant royalties for poinsettia varieties are paid to the Ecke family and, chances are, your poinsettia spent time (either as a cutting or the stock plant from which the cutting was taken) at the Ecke Poinsettia Ranch in Encinitas just north of San Diego).
There are a number of varieties but the most commonly grown red cultivars in Virginia are 'V-14 Glory', 'Celebrate', 'Supjibi' ("sue-jee-bee" or "soup--jee-bee"), 'Heggs', or 'Freedom'.
The colorful part of a poinsettia plant is the inflorescence, which is made up of bracts and cyathia. The bracts are the colored (red, white, pink, or bicolor), leaf-like appendages at the top of the plant. They are, in a taxonomic sense, modified leaves. In the middle of the inflorescence are cyathia that look like small, green balls or cups. Inside each cyathium are the true flowers. You are likely to see yellow, pollen-bearing flowers extending out of a cyathium. On the side of a cyathium, you may see small, nectar-holding structures called nectaries that attract pollinators. Some of the upper leaves also may be the same color as the bracts. These leaves are called transitional leaves.
Extensive laboratory testing and university research has concluded that poinsettias are not poisonous. However, this does not imply that they are edible. In addition, some people develop a skin rash if exposed to the white, milky sap of poinsettias.
Improper water and light, and excessive heat are the leading causes of failure in caring for gift plants like poinsettias. These plants are grown in greenhouses, where the nighttime temperatures are cool, light is adequate, and the air is moist. When they are brought into a dry home, where the light is poor and the temperatures are maintained for human comfort, results are frequently disappointing. Do not expect to keep a gift plant from year to year. Enjoy them while they are attractive and in season, and then discard.
The poinsettia requires bright light and should be kept away from drafts. A temperature between 65 and 70F is ideal. Avoid temperatures below 60F and above 75F. Keep plants well watered but do not overwater - let the soil dry between watering. Some of the newer, long-lasting varieties can be kept attractive all winter.
Gardeners frequently ask whether they can carry their poinsettias over to bloom again next year. The quality of homegrown plants seldom equals that of commercially grown plants. However, for those who wish to try, the following procedure can be followed.
After the showy bracts fade or fall, set the plants where they will receive indirect light and temperatures around 55 to 60F. Water sparingly during this time, enough to keep the stems from shriveling. Cut the plant back to within 5 inches of the soil surface and re-pot in fresh soil. As soon as new growth begins, place in a well-lighted window. After danger of frost, place the pot outdoors in a partially shaded spot. Pinch the new growth back to produce a plant with several stems. Do not pinch after September 1st. About Labor Day, or as soon as the nights are cool, bring the plant indoors. Continue to grow in a sunny room with a night temperature of about 65F. Since the poinsettia blooms only during short days, exclude artificial light, either by covering with a light-proof box each evening or placing in an unlighted room or closet for a minimum of 12 hours of darkness. Plants require full light in the daytime, so be sure to return them to a sunny window. Start the short-day treatment in mid-September to have blooms between December 1 and Christmas.
Virginia Cooperative Extension will be offering Master Gardener classes in Albemarle, Fluvanna, Louisa, & Nelson counties beginning in January. Please call your local Extension office for more information.
Contact your local Virginia Cooperative Extension office and speak with an Extension Agent or Master Gardener volunteer for more advice and information on lawn and landscape topics. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.