Regional Gardening Reports :: National Gardening Association

In the Garden:
New England
December, 2010
Regional Report

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Poinsettias account for the majority of holiday plant sales in the U.S.

Deck the Halls with the Season's Most Popular Plant

It's getting to be that time of year when garden stores, supermarkets and home centers are overflowing with poinsettias. Their cheerful colors- no longer limited just to red, but available now in shades of pink, white, peach, burgundy, even variegated- are a great antidote to winter's grays and browns. And, thanks to breeding advances, poinsettias often remain colorful additions to your windowsills for months after the holidays.

Introduced into cultivation in the U.S. in 1825 by our first ambassador to Mexico, Joel Roberts Poinsetts, for whom it is named, this plant has become not only an enduring symbol of the Christmas season, but has gone on to become the best selling flowering potted plant in the country, accounting for more than 85% of all holiday plant sales. Pretty good work for a Mexican wild flower with nondescript flowers.

True flowers that is. For what we think of as the "flowers" of the poinsettia are in fact colorful modified leaves or "bracts." The true flowers are the inconspicuous, yellowish structures in the center of the ruff of bracts. The bracts develop their characteristic colors after being exposed to a sufficient number of hours of uninterrupted darkness. Commercial growers manipulate the timing of the photoperiod that their plants are exposed to in order to produce poinsettias that are in full "bloom" in time for the holiday season. Once you get your poinsettia home, you needn't worry about the daylength it receives unless you plan to carry your plant over the summer and try for another season of color next year.

But there are a few things to keep in mind when selecting and caring for your poinsettia to keep it looking good as long as possible. When you're picking out a plant to bring home, choose one with deep green leaves and fully colored bracts. Leave any with yellowing, wilting or dropping foliage behind. Look for plants that are symmetrical, full and attractive from all sides. Avoid those that are crowded together, on display encased in plastic sleeves or are sitting in water inside their decorative foil pot cover. And check those tiny true flowers in the center of the "blossom"-- if they are green or tipped with red, your poinsettia will hold longer than if the flowers are covered with yellow pollen.

If it's below about 60 degrees outside, be sure to tuck the plant inside a protective sleeve or large bag for its trip to your car, even if it's just a short dash. Sudden exposure to cold temperatures can cause a poinsettia to drop its bracts and leaves.

And when you do get it home, put it in a spot where it will get bright light, but no direct sunlight, for at least six hours a day, and where it won't be exposed to drafts from doors, windows and heat vents. Daytime temperatures of 68-70 degrees are fine, but night temperatures shouldn't go much below 60 degrees. Remove any decorative wrappings (or at least the bottom of them) so water can drain from the pot and water when the soil feels dry to the touch. You'll be enjoying your poinsettia's bright color not only during the holidays, but when the cold winds of January and February whistle outside as well.

If you decide you're up for the challenge of trying for a second year of color, keep your poinsettia plant in good light, and continue to keep it watered, even after the bracts finally fade. In late March or early April, cut the plant back hard, to about 8 inches, and begin feeding with a complete houseplant fertilizer every few weeks. Around June 1, repot the plant in fresh soil and a container that's no more than 4 inches larger than the original. You can also take cuttings from the new shoots that have grown, root them and grow them on. Either way, your plants will be happiest outside in a lightly shaded spot after all danger of frost is past. Pinch plants regularly as they grow so they become full (but end all pruning by September 1), and bring them back inside before fall frosts threaten.

Then, come October 1, it will be time to do some photoperiod manipulation. For 8 to 10 weeks, your poinsettia will need 14 hours of continuous darkness every night in order to set buds and cause the bracts to color. You can accomplish this by putting the plant in a closet or covering it with a light-proof box every evening -- just remember to put it back on a sunny windowsill it in the morning! Make sure night temperatures stay in the 60 to 70 degree range. Continue your fertilizer regimen during this preparatory phase, but put it on hold once the plant comes back into bloom.

For your efforts, you'll be rewarded with a lovely holiday decoration that you can look at with satisfaction and think "Hey, I did that!"

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