Poinsettias Need Darkness For Color

Patricia M. Arledge, Sharpe, Kenneth W.  |  11/6/2013 12:46:05 AM

News Article for October 7, 2013:

Poinsettias are very popular as a Christmas decoration. The plants are unique with their colorful modified leaves but once you buy then what do you do with them after Christmas? Many people continue to care for them hoping for a second year of Christmas cheer.

If you have kept your poinsettia from last year you will need to know that they have a photoperiod that needs to be met if you are to get color in time for Christmas. This photoperiod is actually the hours of darkness that the plants receive in a given day and then that has to be followed by bright sunlight in the daytime.

Since we just passed the fall equinox we are receiving at little less than 12 hours of sun and a little more than 12 hours of darkness which is ideal if there are no artificial lights around. Unfortunately there are artificial lights all around and they can interrupt the dark period of the night and will delay the onset of color.

In order to get poinsettias to show color for Christmas, growers will start somewhere around the first or second week of October and give the plants 13 -14 hours of continuous darkness for about 40 days. They usually accomplish this by placing the poinsettias in a greenhouse and then covering the house with shade cloth, making sure there are no outside lights around.

It is a difficult task to keep light out of a small piece of property because light occurs from so many sources. Consider security lights, car lights driving up driveways and lights inside the building that could inadvertently be turned on.

You could consider an outside building for nighttime darkness and then move the plants outside daily. Some people will use a closet but you must seal out all light around the cracks and under the door to prevent breaking the darkness period and then take them out into sunlight each day. One other suggestion is that if you have enough land to be away from all artificial lights then just leave the plants outside and let nature provide the normal light and dark periods.

Any interruption in the darkness period will delay color.

For more information on these or related topics contact Kenny at 225-686-3020 or visit our website at www.lsuagcenter.com/livingston.

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