Expert: Christopher Littrell - 5/4/2007

Question
i know it may be a little early to be asking this, but i was wondering how you deal with winter dormancy for cobra pitcher plants?

Answer
Hello Nate,

Darlingtonia can be wintered in the same fashion as Sarracenias so long as their watering requirements are met (cold water running over their roots simulated in various ways). If you live in North America where you can winter the plants outside, they will automatically go dormant when the amount of sun photoperiod reduces during winter and come out of dormancy as the photoperiod increases. They have a dormancy period of about 3-6 months. They can withstand winter cold down to about 30 degrees or so but should be protected from long freezes by mulching or covering the plant with a bag or even bringing the plant into a cold room or garage with a window.

If you have no option but to winter the plant indoors, you will have to simulate dormancy by reducing the photoperiod of light the plant receives at the start of winter by about one hour per week until the plants get 8 hours of light. During this time, you can obtain an ice chest or a cold room in the house to place the plants in so that the temperature reduces to about 40 degrees gradually over the weeks of photoperiod reduction. Some people just get their plants into a dormant state and place them in a refrigerator (not the freezer), however, that might be impractical for reasons of space, fungal infection, drying, and simple unnaturalness of the process. The plants still need to feel the seasonal changes and cannot do that in a refrigerator and what little light is present during winter is still sluggishly used by any green leaves the plants retain during winter. My compromise is the ice chest. I place the ice chest where it can receive 8 hours of light during winter when it is open in the day. I close it at night to drop the temperature down to about 40 at night. The temperature is maintained cold by using gallon and 20 ounce water bottles and jugs frozen solid and placed around the plants. As the light photoperiod reduces, I place a few frozen bottles in the chest with the plant to take the temperature down to about 60 for a week or two, then more bottles enough to drop the temperature to about 50, and finally down to 40 in the last couple of weeks of photoperiod adjustment. Those temperatures are with the chest closed. Open, the chest might be about 10 degrees warmer by day. In any case, replace the frozen bottles with newly frozen ones every 12 hours to keep the temperature down. That setup has successfully been used to stratify Sarracenia seeds and supply dormancy for other North American carnivorous plants without difficulty. In addition, condensation occurs with the frozen water containers, keeping the plants from being freeze dried.

I hope this helps you with some ideas about how to over-winter your plants.