November 2, 2013

1 - It is not too late to start inducing your poinsettia plant to bloom.

Yard and Garden November 2, 2013

Q.

I usually take my poinsettias indoors in mid-September to begin placing them into a closet every night. I did not get that done this year. I took them indoors, but into a room with lights on at night. Is it too late to begin putting them into the closet to make them bloom?

A.

No, it is not too late to begin the long-night treatments. Most varieties of poinsettia plants need 8 to 10 weeks of long, uninterrupted periods of darkness (5 pm to 8 am, 15 hrs.) to induce flowering. If you begin the treatments now, your plants may bloom in time for Christmas, or soon thereafter. The key words in the treatment conditions are "dark" and "uninterrupted". No light should reach the plant during its dark period each and every night. Even the light of a flashlight can delay flowering if you need to enter the room with the plants being treated. It seems that you are familiar with the process of inducing flowering in the poinsettias that you "carried over" from last year, but for other gardeners who have never done this, here are some additional tips. The plants must have light during the day-period (9 hrs.) and they must be kept moist, but not overwatered. A large, sunny south or east window is a good place to keep the plants during the day. Ideal temperatures for growing the poinsettias indoors are approximately 60 degrees at night and 70 to 75 degrees during the day. If moving the plants to a closet each night is too much trouble or impossible, you can accomplish the same effect by covering the plants with a box or fabric that permits the entry of no light. This may be a cardboard box with all seams sealed with opaque tape and then covered with a black garbage bag or thick black fabric. Also, check to be sure that there is no light entering from under the bottom of the box. You must remove the plant from the closet or remove the box and covering each day. Continue this process until the flowers (actually colored leaves called bracts) are fully expanded. Early removal for parties or decoration is OK, but be sure that the bracts are well colored and mostly expanded when you do this. The further development of the bracts' color development may be impaired by early removal, but the plant will to be harmed.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

Links:

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!