This article appeared in the November-December 2001 issue of Horticulture Update,
edited by Dr. William C. Welch, and produced by Extension Horticulture,
Texas Cooperative Extension, The Texas A&M University System, College Station, Texas.
History of the Poinsettia
Native to Mexico, the poinsettia originated in a region near the present-day city of Taxco. Joel Robert Poinsett, a Southern plantation owner and botanist, was appointed the first United States Ambassador to Mexico (1825-1829). While visiting Taxco, he was struck by the beauty of the brilliant red plants he found blooming in the region during December. He had some of the plants sent to his plantation in Greenville, South Carolina, where they flourished in his greenhouse. While the botanical name, Euphorbia pulcherrima, was given by a German taxonomist in 1833, the common name, poinsettia, became and has remained the accepted name in English-speaking countries. With over 70 million plants sold nationwide each year, the poinsettia is now the number one flowering potted plant sold in the USA.
The widespread belief that poinsettias are poisonous is a misconception. The safety of poinsettias in the home is demonstrated in scientific studies conducted by Ohio State University in cooperation with the Society of American Florists. The study concluded that no toxicity was evident at experimental ingestion levels far exceeding those likely to occur in a home environment. In fact, the POISINDEX Information Service, the primary information resource used by most poison control centers, states that a 50-pound child would have to ingest over 500 poinsettia bracts to surpass experimental doses. Yet even at this high level, no toxicity was demonstrated. As with all ornamental plants, the poinsettia is not intended for human or animal consumption.
How to Select a Beautiful Poinsettia
Look for plants with fully mature, thoroughly colored and expanded bracts, i.e., the colorful parts of the poinsettia. Avoid plants with too much green around the bract edges. Bracts come in white, pink, peach, yellow, marbled or speckled, as well as the traditional red. An abundance of dark, rich green foliage is a vital sign of good plant health. Look for plants with dense, plentiful foliage all the way down the stem.
Shape and Proportion
Proper proportion of plant height and shape relative to container size is the key to an aesthetically pleasing poinsettia. Plants should appear balanced, full and attractive from all angles. A generally accepted standard is that the plant should be approximately 2-1/2 times taller than the diameter of the container.
Durability and Freshness
Select plants with stiff stems, good bract and leaf retention, and no signs of wilting, breaking, or drooping. Be wary of plants displayed in paper, plastic, or mesh sleeves. A poinsettia needs its space; the longer a plant remains sleeved, the more the plant quality will deteriorate. Examine the soil of the plant. Itís best to avoid waterlogged soil, particularly if the plant appears wilted. This could be a sign of irreversible root rot. When transporting the plant, protect it from chilling winds and temperatures below 50 degrees F. Re-inserting the poinsettia into a sleeve or a large, roomy shopping bag will usually provide adequate protection for transporting the plant home when it is cold and windy.
How to Care for Poinsettias at Home
Location and Temperature
The poinsettia thrives on indirect, natural daylight, and exposure to at least six hours daily is recommended. If direct sun cannot be avoided, diffuse with a light shade or sheer curtain. To prolong the bright color of the poinsettia bracts, daytime temperatures should not exceed 70 degrees F. Avoid placing the plants near drafts, excess heat, or the dry air from appliances, fireplaces, or ventilating ducts.
Water and Fertilizer
Poinsettias require moderately moist soil. Water the plants thoroughly when the soil surface feels dry to the touch. Remove the plant from decorative pots or covers, and water enough to completely saturate the soil. Do not allow the poinsettia to sit in any standing water; root rot could result which could kill the plant. It is not necessary to fertilize the poinsettia when it is in bloom.
Since poinsettias are sensitive to cold weather, frost, and rain, outside placement during the winter months should be avoided. However, in mild climates, an enclosed patio or entry way may be suitable, provided the night temperatures do not drop below 55 degrees F. Make certain the delicate bracts are well protected from wind and cold rain.
After the Holidays
Keep the plants in indirect sun and water regularly. Place your plants outdoors, where they can bask in the warmth of spring and summer, after outside night temperatures average 55 degrees F. or above. When the bracts age and lose their aesthetic appeal, usually by late March or early April, cut the poinsettia back to about 8 inches in height. By the end of May you should see vigorous new growth. Continue regular watering during the growth period. Fertilize every 2 to 3 weeks throughout the spring, summer, and fall months with a well-balanced, complete fertilizer. Around June 1, you may transplant your poinsettias into larger pots. Select pots no more than 4 inches larger than the original inner pot. A soil mix with a considerable amount of organic matter, such as peat moss or leaf mold, is highly recommended. If you wish, you may transplant the poinsettias into a well-prepared garden bed. Be sure the planting bed is rich in organic matter and has good drainage. Pruning may be required during the summer to keep plants bushy and compact. Do not prune after September 1.
The poinsettia is a photoperiodic plant, meaning that it sets bud and produces flowers as the autumn nights lengthen. The plants will naturally come into full bloom during November or December, depending upon the flowering response-time of the individual cultivar. Timing the bloom to coincide closely with the Christmas holiday can be difficult without the controlled environment of a greenhouse. Stray light of any kind, such as from outside street lights or household lamps, could delay or entirely halt the re-flowering process. Starting October 1, the plants must be kept in complete darkness for 14 continuous hours each night. Accomplish this by moving the plants to a totally dark room, or by covering them with a large box overnight. During October, November, and early December, the plants require 6 to 8 hours of bright sunlight daily, with nighttime temperatures between 60 and 70 degrees F. Temperatures outside this range may delay flowering. Continue the normal watering and fertilizer program. Following this regime for 8 to 10 weeks should result in a colorful display of blooms for the holiday season.
RETURN TO HORTICULTURE UPDATE