Issue: October 14, 2000

  • Cold injury above f1eezing
  • Germinating Virginia creeper seeds

Cold injury above freezing


Will a temperature of 33 degrees Fahrenheit hurt any type of common houseplant or outside plants?


The answer is yes! Many plants can withstand temperatures below freezing, many can tolerate temperatures near freezing, but some cannot tolerate low temperatures even when the temperature is above freezing. The time the plant must endure the cold temperature is also a consideration. Longer durations at a low temperature will result in more injury.

Many houseplants are from the tropics and very sensitive to low temperatures. As a student, I grew a plant called flame violet (Episcia) that died each year just after the Christmas vacation. When I went to my parents' home during the Christmas holidays, I set the thermostat at 50 degrees in my apartment. Later, after several dead plants, I realized that the low temperature killed my flame violet. By keeping the temperature near 60 degrees, subsequent flame violet plants survived without injury. I believe this is one of the most sensitive plants to "chilling injury", but there are many others, including common garden annual vegetables and flowers, which will also exhibit injury at low temperatures above freezing.

I must also ask how you are measuring the temperature. Temperatures measured in one location may vary by several degrees from temperatures in a nearby location. Low temperatures reported by the news or weather service may vary considerably from the temperatures in your garden. If you measured a temperature of 33 degrees or heard it reported on the news, it is very likely that temperatures below freezing existed somewhere in your landscape. If your question is based on the observation of frost damage when your thermometer said it didn't freeze, this is probably the explanation.

Germinating Virginia creeper seeds


How does a person germinate seed for a Virginia creeper vine?


Seed of the Virginia creeper may be germinated by planting them in the fall or by "stratifying" them in moist vermiculite or peatmoss for eight weeks in a refrigerator at 40 degrees before planting them outdoors or in pots. The required cold exposure is usually provided by the winter temperatures if the seed are planted outdoors, but you can speed germination by storing them in moist vermiculite or peatmoss in the refrigerator for a while before planting. They may be kept in plastic bags, or any other sealed containers, so that they do not dry while in the refrigerator.

This "stratification" treatment is standard practice for seeds of plants from temperate climates. Under natural conditions, they must overwinter before they will germinate. We must provide conditions to simulate winter conditions before they will germinate. Tropical plants, on the other hand, do not have this requirement for germination.

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Send your gardening questions to Yard and Garden, ATTN: Dr. Curtis Smith NMSU Cooperative Extension Service 9301 Indian School Road, NE, Suite 112 Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

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