   Poinsettias - December 25, 2013 Jeff Schalau, Agent, Agriculture & Natural Resources University of Arizona Cooperative Extension, Yavapai County Today’s poinsettia cultivars come in a wide range of colors and a variety of bract shapes and sizes. Many gardeners know that it is the bracts and not the flowers which display the seasonal color of poinsettias. A bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower. Ongoing poinsettia research has also produced cultivars that have stronger stems and better “keeping” qualities. This column will provide care tips that will extend the life of your poinsettias well beyond the holidays. Poinsettias thrive on bright, sunny natural daylight: at least six hours daily is recommended. Placement near a sunny window is ideal, but avoid locations where hot afternoon sun may shine directly on, and fade colorful bracts. To prolong the bright red of the bracts, temperatures ideally should not exceed 70°F during the day, or fall below 65°F at night. Avoid placing poinsettias near drafts, fluctuating air currents, excess heat and dry air from appliances, fireplaces or ventilating ducts Water your poinsettia thoroughly when the soil surface feels dry to a light touch. Like other container plants, the best indication of a thorough watering is water begins to seep through the drain holes at the bottom of the pot. Pour off any excess water, as poinsettias left sitting in water may suffer from root rot. It is not necessary to fertilize your poinsettias during the holiday season. However, for those that want to grow their poinsettias beyond the holidays should apply a balanced, all-purpose household plant fertilizer after the holidays to promote new growth. Poinsettias are sensitive to cold temperatures and outside placement during the winter months is not recommended at Arizona’s higher elevations. Leaf drop will occur if poinsettias are exposed to temperatures below 50°F. Exposure to frost will usually kill a poinsettia plant. Poinsettias can be grown year round for lush green foliage. In March or April, when the bracts age and turn to a muddy green, cut the stems back to about eight inches in height. After you cut the plant back, it will probably look rather stark, with bare branches and bluntly cut stems. By the end of May, you should see new growth. Keep the plants near a sunny window. Around July 4th, cut branches back again about half their length to encourage bushy plants. You may place your poinsettias outdoors in indirect sun when night temperatures are warmer. Continue to water the plants regularly during the growing period. Fertilize every 2 to 3 weeks throughout the spring, summer and fall months with a complete, indoor plant fertilizer. The poinsettia is a photoperiodic plant, which means it begins to set buds and produce flowers as the summer days become shorter. The plants will naturally bloom during November or December depending upon the flowering response time of the particular cultivar. This can be tricky to do outside of a controlled greenhouse environment, because any stray artificial light could delay or halt the flowering of the plants. Now comes the tricky part: starting October 1, the plants must be kept in complete darkness for 14 continuous hours each night. This can be done by moving the plants to a dark room, or placing a large box over them. During this period, the plants require 6 to 8 hours of bright sunlight and night temperatures between 60 and 70ºF. This regimen must continue for approximately 8 to 10 weeks in order for the plants to develop colorful bracts for the holiday season. If this seems like an exercise for people with too much time on their hands, support the horticulture industry by purchasing another poinsettia. Poinsettias are one of the big commercial greenhouse crops in many parts of the U.S. About 4,428,000 potted poinsettias were sold in 2012 which had a wholesale value of $17,627,000. By the way, the blue and purple poinsettias have been sprayed with a dye to give them these unique colors. I have linked other poinsettia information below. Follow the Backyard Gardener on Twitter – use the link on the BYG website. If you have other gardening questions, call the Master Gardener help line in the Camp Verde office at 928-554-8999 Ext. 3 or e-mail us at verdevalleymg@gmail.com and be sure to include your name, address and phone number. Find past Backyard Gardener columns or provide feedback at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. Additional Resources All About Poinsettias, Backyard Gardener, December 27, 2013 http://ag.arizona.edu/yavapai/anr/hort/byg/archive/poinsettias.html Poinsettias, Colorado State University Extension http://www.ext.colostate.edu/pubs/garden/07412.html  |