November 18, 2010 at 9:31 a.m.
The poinsettia is a euphorbia in a class of its own. It was first found in Mexico in 1825 by the first U.S. Ambassador to Mexico, Joel Poinsett. The ancient Aztecs used the poinsettia for a variety of purposes. The bracts were made into a reddish purple dye and the plant's latex was synthesized into a fever medicine. The poinsettia, which can grow to become a shrub in its native habitat, blooms during the season of Advent in December and so it's used to adorn nativity scenes and other Christmas displays.
Joel Poinsett, as an amateur botanist, eagerly brought the plant from Mexico back home with him to South Carolina. Though not initially popular, pointsettias found their way to Florida and California and grew quite well in those warmer climates. In 1902 German immigrant Albert Ecke noticed poinsettias growing as wild flowers in California. He and his family began growing them as cut flowers. It wasn't until 1920, after many years of selection, that Paul Ecke Sr. developed a cultivar with a compact growth habit suited to container culture. Due to Ecke's efforts, the poinsettia has become a traditional symbol of Christmas.
If you buy a poinsettia this holiday season for yourself or someone else here are some tips for keeping it looking its best this winter.
Make sure the plant is wrapped well when you bring it home and unwrap it right away. Even a few seconds of frost can kill a poinsettia. For good photosynthesis, expose it to at least six hours of bright sunlight daily. If you don't plan on keeping the plant past the holiday season, it can be kept in dim light, as the plant will live off stored energy. Avoid cold, drafty locations as well as heat sources such as fireplaces or hot air ducts. Chilling can cause leaves to turn yellow and drop, while hot air causes wilting and drying. Poinsettias prefer temperatures no higher than 72 degrees. Dropping the temperature by 10 degrees at night helps prolong the bract color. Nighttime temperatures should be no lower than 55 degrees. Water soil thoroughly with lukewarm water when the surface feels dry. Over watering will result in root rot, which will kill the plant so provide good drainage. Don't let the plant get too dry, as the leaves will wilt and fall off. Begin monthly fertilization after you've had the plant about six weeks using houseplant food mixed at half strength. If you don't plan on keeping your poinsettia past the holiday season, fertilization isn't necessary.
Getting a poinsettia to rebloom can be no easy matter.
The poinsettia is a photoperiod plant, which means it begins to set buds and produce flowers as the nights become longer. The plants will naturally come into full bloom during November or December depending upon the flowering response time. This can be tricky because any stray artificial light such as a street light or a house lamp would delay or halt the re-flowering.
Starting in October, the plants must be in complete darkness for 14 continuous hours each night. To do this, place them in a dark room or put a large box over them. During this period the plants require six to eight hours of bright sunlight and temperatures between 60 degrees and 70 degrees. This process must continue for approximately eight to 10 weeks in order for the plants to develop a colorful display of blooms for the holiday season. Once you see the flowers developing, that is when the floral bracts start to show definite color, you do not have to continue the dark treatment.
Contrary to popular belief, poinsettias are not poisonous but the sap can be slightly irritating to the skin. No part of the plant is intended for human or animal consumption.
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