January 10, 2009

1 - Poinsettias will freeze outside in New Mexico.

Yard and Garden January 10, 2009


We are new to the area and live in Placitas. Is there any chance that our beautiful, large poinsettia will survive being planted in Placitas?

- Dianne


Now is not a good time to plant any of the holiday flowering plants you received this year. Plants that have been inside a warm home will freeze if planted outside now. Even plants that can survive the winter outdoors will die if they are actively growing now and planted outside. The poinsettia is not hardy even if it has grown outside all summer, so it will definitely not survive if you plant it outside. It must remain a container plant to be moved out for the summer and indoors before a frost kills it. Some gardeners decide it is easier to purchase a new plant next year, but other gardeners enjoy the challenge of growing and reblooming these plants.

If you received dormant, bare-root plants (fruit trees and such) or dormant hardy bulbs, these plants can be planted outside. A common gift at this time of the year is an amaryllis bulb. It is not hardy and must be planted in a pot and kept indoors during the winter (follow the planting directions that came with the gift bulb).

Many gift plants, and other holiday plants, such as your poinsettia, can be taken outside for the summer. Most houseplants will be strengthened if summered outside and then returned to a bright location indoors for the winter.

2 - It is difficult to force lilac twigs to bloom early indoors.


In early December I cut some twigs from my lilacs and put them in vases indoors. I had hoped that they would bloom and provide flowers for the holidays. The house was nice and warm, but the lilacs did not grow or bloom. What is wrong?


If you had waited until about February it may have worked. The lilacs probably had not accumulated enough "chill units" to induce flowering. Lilacs and many other temperate zone plants have a dormancy mechanism in their buds (and seeds) that protects them from beginning to grow too early. During the winter they "count" the cool days by measuring the accumulation of gibberellic acid, a naturally produced hormone that stimulates bud growth. This process occurs at temperatures below 50 degrees and above freezing. Below freezing, no gibberellic acid is created and above 50 degrees, the gibberellic acid is lost. So, only temperatures between freezing and 50 degrees count.

Next year, if you want to try this again, harvest the twigs early (as soon as the leaves fall from the lilacs) and then store the twigs wrapped in moist sphagnum moss or paper towels in the refrigerator (not freezer) for about 2 months. When you take them from this cold storage, place them in vases of water and they may bloom. The benefit of the refrigerator is that the temperatures remain constantly at the proper temperatures, so it takes less time than outdoors where the temperature is constantly varying and often outside the proper range.

There are no guarantees, but this is an interesting experiment for gardeners who are inclined to experiment.

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.


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!