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Index : Container Plants & Patio Gardening
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- 26. Poinsettias Is Christmas Favorite - Top
- By far, the most popular of all Holiday plants is the poinsettia. Not even the amorous appeal of mistletoe can compete with this relatively modern Christmas favorite.
The poinsettia is a native of Mexico and Central America. It was introduced into this country in 1825 by Joel Poinsett, at the time United States Ambassador to Mexico. A less than popular ambassador, there are many in Mexico still resentful that the flower is named after Poinsett.
In tropical and subtropical climates poinsettias are popular landscape plants, growing to a height of 10 feet or more. Here in Tucson, poinsettias can be planted and grown outdoors. They are cold sensitive and will freeze back to the ground, but will regrow in the spring.
Poinsettia belongs to the genus euphorbia. It’s relatives include crown of thorns, pencil tree and gopher plant. All are succulents with milky sap that can cause skin irritation. Poinsettias, however, contrary to popular belief are not poisonous! That was proven by researchers at Ohio State University more than 20 years ago. The researchers there tested the effects of eating unusually high doses of every plant part, from roots to sap. Their results indicated, for example, a child could eat 500 to 600 poinsettia leaves and not show any sings of poisoning. Studies conducted since then have backed up these findings.
The color of poinsettias are not provided by their flowers, but rather by modified leaves on the stem ends called bracts. These bracts turn red in response to the shortening of daylight in Autumn. The true flowers of the plant are small, green and yellow nubs clustered in the centers of the bracts.
Poinsettias have been greatly improved since their introduction in 1825. Not that long ago, poinsettias retained their colorful bracts for only a week or so. Modern day cultivars, mostly bred by Ecke’s Poinsettia in Encinitas, California, will retain their color for months. Modern breeding has produced an array of choices. Most plants are now compact and bushy, some miniatures no taller than 6 inches. Bract colors come in red, pink, and white. Mixed color bracts are even available in the popular ‘jingle bells’ varieties. Florist shops and garden centers usually have a good selection of colors and types.
When selecting a poinsettia, choose one that has health green leaves. Pass up plants with yellowing leaves or brown leaf tips or margins. Poinsettias at their peak will have bright colored bracts. Faded color means the plant is past it’s prime. Overly mature plants may also be producing pollen from the flowers. This pollen will appear as a yellow dusty discoloration on the bracts.
In the home, poinsettias should be placed in draft-free locations. They like cool night temperatures, so locate them away from fireplaces, televisions, lamps or other heat sources. Bright, indirect light is best during the day. Today’s poinsettias are mostly trouble-proof, with one exception. Allowing the soil moisture to fluctuate greatly from wet to dry will cause leaves and bracts to drop off. Keep soil evenly moist, not wet or dry.
Poinsettias can be planted out in the landscape come spring, after the danger of frost has passed. Here in Tucson that’s usually the middle of March. Find a spot protected from wind and afternoon sun. After planting, cut the top back to 12 inches above the ground. As new growth reaches 12 inches in length, cut the stems back so that just four leaves remain on each shoot. This should be repeated with each successive flush of new growth until mid-September. These successive prunings will keep the plant compact. New growth after mid-September will initiate flower buds in October.
It is essential that poinsettias receive no light at night during the bud-setting period. Poinsettias require a long, dark period before they will initiate flower buds. Normally, they set flower buds in early October when nights are becoming increasingly longer. If the dark period is interrupted with the light from a window, street light or any other light source, flowering will be markedly delayed or the plant may not flower at all. Just a short interruption in the night-time darkness is enough to delay or prevent flowering. This should be kept in mind when selecting a location for planting. Of course, you can cover the plant with a large box or other light screening device at night if an appropriate location can’t be found. Place the cover over the plant at 6:00 p.m. and remove it at 8:00 a.m. each day.
For poinsettias planted outdoors, begin fertilizing in April. Continue fertilization with a flowering plant food on a monthly basis through September. The soil should be kept moderately moist at all times. A 3 inch layer of wood chips placed over the soil will help hold in soil moisture.
Finally, remember to protect poinsettias from late Fall and early Winter chills. Plants should be covered when temperatures approach freezing. After blooming, plants can be allowed to freeze back to the ground but should be heavily mulched to protect the roots and stem bases
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona 626-5161.
Material originally appeared in Arizona Daily Star gardening column, on December 6, 1998
- Updated: April 20, 2001
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