I have noticed poinsettias for sale already. How do they get them in bloom so early? If I buy one now, will it last until Christmas?

Just like everything else associated with Christmas, poinsettia plants are in the stores by mid-November.

Poinsettias were originally selected as a Christmas flower because they bloom naturally starting about mid-December when planted outside in sub-tropical climates where the temperatures stay above freezing all year. Then they discovered that poinsettias, just like many other plants, are sensitive to photo period. They are naturally triggered to bloom in the shortening days of the fall. They are referred to as short day plants. But it is actually the longer nights which trigger bloom.

Another example is the natural color change and leaf drop of common trees like maple.

We think it is the colder weather which causes leaf drop. However, maple trees in warmer climates like California drop their leaves at about the same time as here.

Greenhouse growers simply start covering poinsettia plants in the afternoon with black cloth to shorten the days 2 or 3 weeks earlier in the fall so they will bloom earlier.

Poinsettia varieties have been bred over the last few years so that they will retain their flower bracts until well after Christmas when given the proper light, temperature and moisture conditions.

Poinsettias placed where they get cold drafts of air from opening and closing outside doors will often drop flower bracts or leaves early. Keeping the roots too wet by too frequent watering, or letting plants dry out so that they wilt, can also cause premature leaf and flower drop. Inadequate light can also cause leaf and flower drop.

The best place to put plants for long term beauty is in a well-lighted area such as near a window or where artificial lights are left on all day. They should be away from sources of outside cold air. If purchased on a day when the temperature is below 45 degrees, plants should be covered when carrying them from store to car. The car should be warm inside also. Don’t leave a plant in the car while you make other purchases.

Water plants regularly when they are dry on the top, but still moist underneath. Normally, about once a week is adequate. The outside foil wrap can trap water which has drained from the pot. This water is then reabsorbed by the soil and it stays too wet. When soil stays saturated with water there is not adequate room in the soil pores for oxygen. Without adequate oxygen, roots die and leaves and flowers are dropped by the plant. Either remove the foil wrap when you water or punch holes in the wrap so water will drain through.


Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.

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