The Carnivorous Plant FAQ v. 11.5
- courtesy of -
The International Carnivorous Plant Society

Q: About dormancy requirements.

A: Some parts of the world do not experience much seasonal variation. For example, the tropics stay warm year-round. Carnivorous plants such from these regions, such as Nepenthes, may be grown all year. The weather is always fine!

But most carnivores grow in habitats that are inhospitable during some season. To survive these times, plants either produce seed and die or they enter a dormant resting period. If you attempt to grow a plant that anticipates a resting period, you must respect its dormancy requirements or else the plant will simultaneously try to both grow and rest, and in the resulting confusion it will languish and perhaps even die.

A fair analogy is that humans must sleep for several hours each day, regardless of whether they experience night. Humans in places without nighttime, such as the polar regions of the Earth during the summer or the Las Vegas casinos during any season, must eventually sleep.

Different plants enter dormancy during different seasons. Many carnivorous plants rest during the cold of winter by forming tightly bound hibernacula or turions---some Drosera, Pinguicula, and Utricularia are notable for this. Some sundews such as Drosera binata may stop growth and die back to the soil without forming any obviously specialized structure beyond a thick root system. Other plants, such as Sarracenia, Darlingtonia, or Dionaea (Venus flytraps), simply slow or stop growth.

Cold is not the only enemy. Excessive heat is another reason plants may hibernate. The Drosera of Western Australia are famous for their adaptations to the dry hot summers. The tuberous species regress to an underground corm for several months of the year. Simultaneously, the delicate pygmy species stop growing and try to survive the heat and desiccating winds by hiding within the shade of their dead leaves and stipules from the previous season's growth.

Venus flytraps and Sarracenia have a cool dormancy period of about three months. These plants desire chilly temperatures, but still expect some sunlight. When you are trying to determine what kind of dormancy conditions you should provide, think about the native habitat for these plants. Venus flytraps are from the Carolina coastal regions. It gets pretty chilly there, although rarely do they experience a freeze!

If you are puzzling how to provide a dormancy, read the FAQ entries on Venus flytrap dormancy temperature ranges and especially methods on how to provide winter dormancy, as they apply to many common carnivorous plants.

It does not matter if you could provide your plant with luxuriant conditions year-round. If your plant wants to enter dormancy you must provide an appropriately cold or hot resting period. Some growers do not like this because they want to enjoy their plants every day of the year. They try to devise ways of keeping their plants awake past their bedtime! This is never very successful. Instead, grow some plants that are active during the winter, and some that are active during the summer---this of course is a great way to feed the mania of collecting plants and to justify enlarging your collection.

Page citations: Lowrie, A. 1987, 1989, 1998; Meyers-Rice, B.A. 2002; Rice, B.A. 2006a; Schnell, D.E. 2002a; personal observation.

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Revised: January 2007
©Barry Rice, 2005