Question
QUESTION: Hello,
I am a graduate student working with a subspecies of Sarracenia purpurea (Sarracenia supsp.var montana)or the Mountain purple pitcherplant. What I am wondering about is their dormancy period. I have about 20 plants that I am working with, monitoring looking at certain interactions but now that the weather is beginning to get cool I am wondering if I need to put the study on hold and if I will need to keep feeding them over the winter? While I have learned a great deal about plant/prey interaction I am afraid I am still a novice about just the plants themselves. Can you help? I am in Athens, GA so we won't get a ton of snow or anything, and these plants are actually used to the North Georgia mountains but any help you can provide would be greatly appreciated.

Thanks,

ANSWER: Hello Kristina,

Since Athens, Georgia is zone 7, you will need to provide some dormancy for the plants. This would take about 3-4 months and require temperatures down to about 40 for most of that time. Before overwintering them, you will need to ensure that the plants are ready for dormancy due to shorter daylength cues. If the plants receive natural sunlight, they will receive those cues seasonally. If they are indoors and receive only florescent light, or artificial light, they will need timed daylengths of light that shorten by one hour a day each week. This will begin from about this month and into November until the plants receive 8 hours or less of light per day. this will cue the plants that winter approaches. Once they are producing protective hormones, you can begin cooling them artificially or outside. If you grow them outside, just ensure that they are protected from any potential deep freeze as they can easily freeze dry in pots. Mulching and tarps or other protective measures can help out as with any other overwintered plant.

Sarracenia do not absolutely have to be fed, but they obtain valuable fertilizers and nutrients from captured insects. They typically do not have any insect prey during winter. As a matter of fact, most of the leaves should be clipped to a few inches of the ground, leaving only newer leaves to give the plant some photosynthesis after dormancy is over in about February to early March.

May your study be informative,

Christopher

---------- FOLLOW-UP ----------

QUESTION: Again, just curious but if we wanted to stall can the dormancy period be put off using artificial lights without harming the plants in order to keep feeding? (feeding is part of the study). Or will the plants shut down on their own sensing mother natures timetable?

Answer
Hello Kristina,

That is a very good question. In general, from what I can tell of Sarracenia Dormancy, the Plants exhibit innate dormancy where the plants tend to have a cyclic growth period, however; they still rely on seasonal cues from light photoperiod and temperature to inform the plants when to induce full dormancy.

Examples: I have grown young Sarracenias from seed in which the plants can be grown year round without dormancy for one or two cycles, then regular seasons are introduced. Since the plants are young and still growing, they can be tricked into continuing growth so long as conditions are favorable and light levels high enough for survival.

In adult Sarracenia, I have noticed that the plants tend to slow down some near winter and begin to grow again even in cold temperatures and low light levels in spring. They do seem to have an internal clock, however; if the plants are kept in extended favorable conditions, they will continue some normal activity. The problem with this is twofold: 1. The plants can expend most of their energy levels trying to maintain growth, eventually weakening and dying; and 2. The slower growth rate could have an effect on the data in your study since the plants themselves will be "waiting" for dormancy anyways.

Your best bet would be to begin your study in early spring with newly pitchering plants and then to extend the study for as long as you need to up to fall. In that way you will not have skewed data from plants slowing down and trying to go dormant. You could even set up annual studies in which you collect data over several years from the same plants so that you have longitudinal data to reference on a seasonal basis.

The problem with florescent lights would be that you would need to have a large enough number of high enough intensity to maintain health in your plants. Sarracenias are full sun plants that require upwards of 25000 to 50000 lumens of light energy in full growth. I have a florescent light set up that provides about 30000 lumens or more at 1 foot distance from the center of the light banks. Less than that can cause slower growth and weakening in your plants. Sarracenia purpurea are the most light intensive plants of the Sarracenia genus, so 25000 lumens would be about the lowest end of the spectrum you could go with.