Institute of Food and Agricultural Sciences
Hendry County Horticulture News
Poinsettia - A Christmas Star
Poinsettias are most widely known as a colorful indoor ornamental potted plant for the Christmas trade. Here in South Florida, they can also be used as outdoor landscape plants and grow into quite large shrubs. Poinsettias are native to Mexico and Central America, where they can grow to be 12 -15 feet tall.
The poinsettia, Euphorbia pulcherrima Willd., is a member of the Euphorbiaceae or spurge family. The name - poinsettia - is in honor of Joel R. Poinsett of Greenville, South Carolina, who during his tenure as the United States Ambassador to Mexico, introduced this plant from Mexico in 1825. Poinsettias are sometimes referred to as Christmas star, which is from its rosette like arrangement of brightly colored bracts that form at the ends of the stems in the winter months around Christmas time. In Spanish, the poinsettia is known as "flor de pascuas."
The showy part of the poinsettia, which is commonly referred to as the flower, actually consists of modified leaves which are correctly called bracts. The bracts are typically red but can vary depending on the cultivar. Cultivars sporting pink, cream, white, pale green and even mixed colors have been developed by plant breeders. The actual flowers are insignificant little nubs that are arranged above the colorful bracts in umbel-like groups consisting of a single female flower surrounded by a number of male flowers which are reduced to stamens only.
Poinsettias are traditionally grown as pot plants for the Christmas holiday season. Poinsettias are often used as landscape plants in south and central Florida. Poinsettias are woody perennials and when grown outdoors usually begin blooming (bracts showing color) as early as Thanksgiving. The colorful bracts are retained until March or even later if the plants are not exposed to freezing temperatures.
The purchase of a poinsettia is a once-a-year event for most people. Most people don't know what to look for in a quality poinsettia. Here are a few basic tips on what to look for in a poinsettia. These pointers can make a difference between a plant that will look good for the season and one whose appeal quickly fades. If possible, select a plant that has green foliage nearly to the soil line. Older plants that have suffered unfavorable conditions will have usually experienced excessive leaf drop. Foliage drop can be caused by fluctuating temperatures, gas fumes, soil problems, and plant pests. Next look in the center of the bracts and you will see the true flowers called cyathia. This tiny cluster of flowers is one of the best indicators of a poinsettia's freshness. Select only plants with small tight green button like floral parts. These little flowers will eventually develop into open flowers. If the poinsettia is already producing pollen, the plant is past it's peak. This indicates that a portion of the plants useful display life has already passed and the bracts will begin fade early than a similar plant which has not yet begun producing pollen. Poinsettia prices are normally based on the number of bracts and the size of the plant and bracts.
Now that you have selected or received a beautiful poinsettia or more, how do you care for it? Poinsettias can be kept looking attractive far into January or even February if properly cared for. Since most potted poinsettias are the product of the greenhouse, they should be provided as much natural light as possible. At least six hours of bright, but not direct light is required for best results. Poor light or a rapid change in light regime can cause leaf drop. Avoid placing the plant near windows, doors, fans, and heating vents since poinsettias cannot tolerate drafts, which may trigger leaf drop. Poinsettias prefer moist soil, so water regularly. Over watering or allowing the soil to dry out completely can cause leaves to drop. Poinsettias will do best in the more humid areas of the home, such as the kitchen, otherwise they can be placed above but not in a tray of water to increase humidity. It is also wise to place plants away from busy areas where they will be brushed against and bruised. Fortunately, the newer varieties of poinsettia are fairly hardy and will tolerate a bit of abuse.
In the spring, when the bracts begin to fade, the plants should be kept cool and dry for a few weeks. After this resting period, prune the plant back to about six to eight inches high. Remove any remaining colored bracts and leave three to four green leaves per shoot and restart growth by watering and fertilizing with a balanced complete fertilizer every few weeks. By May-June, the plant should display a lot of new growth. At this time, the poinsettia should be transplanted to a 2-4 inch larger in diameter pot and all the shoot tips pruned off. Two to three leaves should be left on each shoot. Fertilize every three to four weeks and keep the plant pinched back regularly until September. In late September, the plant must be given a special dark treatment to promote flowering.
Poinsettias are among a group of plants known as short-day plants. Short-day plants require a long dark period to initiate the formation of flower buds. Poinsettias need 9 to 10 hours of light with 14 to 15 hours of darkness to promote flowering. In nature flower buds are set around October as the night become increasingly longer. In the house, the short day - a long night regime must be produced artificially. This can be done by putting the plants in the closet or covering them with a completely opaque cloth, a box or a black garbage bag. Poinsettias are very finicky about photoperiod. Any interruption of the dark period may result in a failure to blossom. By December, the plant should have initiated flowering and the development of colored bracts. Many pink and bicolor cultivars may revert to red or white when grown inside. Once this occurs, the dark treatments can be stopped and the plants treated like normal house plants again. If handled properly, your poinsettia should produce beautiful blooms for Christmas.
I wish you all a Merry Christmas and the best for the New Year.
Gene McAvoy is the horticulture agent with the Hendry County Extension Service. Direct your horticulture questions to PO Box 68, LaBelle, FL 33975, e-mail - email@example.com or phone 863-674-4092 or 863-983-1598. You are also welcome to visit the Hendry County Extension Office at 225 Pratt Blvd., LaBelle. Office hours are from 8:00 - 5:00.
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