Expert: Christopher Littrell - 1/11/2012

Question
I remember what you said about the dormancy for the venus flytrap and my pitcher plant Purpurea. I've not put the outside yet though because I'm extremely afraid the cold will kill them and not help with dormancy. It's been getting to be around the 'teens' some nights and most nights it's 20's-30's.

Would it still be ok to put them outside or is this too cold? I live in zone 6, in Pennsylvania, if that helps any.

Thanks!

Answer
Hello Devon,

The plants you have are zone 7, for the Venus Flytraps, and variable zones for the Sarracenias, with the Purple Pitcher Plant found in a range of zones from 4-7. The main thing to think about with dormancy is that plants die when they are frozen solid and dry out. Potted plants tend to be more susceptible to this freeze drying, so that is why they need additonal tarps, mulch and the like when we grow plants outside their zone and/or in pots. Even the Purple Pitcher Plant would be in jeopardy in zone 6 even though it can survive zone 4 weather simply because it is in a pot now. The ground provides more insulation than a pot.

Some remedies to get your plants in dormancy would be to first ensure that they are ready for dormancy. They ready themselves by producing hormones to protect their cells from freeze drying and shattering. Those hormones are produces when the plants receive slightly shorter day lengths of light over time. In Fall, the days shorten a few minutes at a time until there is simply less daylight by Winter. You would need to ensure your Venus Flytraps and Sarracenias feel that kind of change over time.

What I do with my artificial lights is simply set the timer to go off one hour early each week until the plants are getting 8 hours of light a day. This takes a good month or two. Once that is done, the Venus Flytraps and Sarracenias will be ready for cold temperatures.

I place mine in a ice chest with ice packs or frozen bottles of water that I replace periodically every 12 to 24 hours as needed. I open the chest in the day to provide air and some light and close it by night to lower the temperature to about 40 degrees. This has worked consistently to keep my plants alive and healthy for over 5 years.

In your situation, take about a month geting the plants to 8 hour days. You can skip an hour or two each week to speed the process so long as the day lenth gradually gets shorter over time to 8 hours. For instance, if you have the light on for 14 hours a day now, you can go to 12 hours per day for a week then 11 hours then 9 hours then 8 hours on the final week. It is better if you can make it more gradual and take a couple months, but Winter is already here and the plants need dormancy.

Once they are down to 8 hour daylengths, you can start cooling them down. You can do this with the ice chest method, which is labor intensive, but really all I have in a place that barely has a winter at all. You can also just place the plants right against a window where they will chill down to about 40 degrees from outside Winter temepratures. You can place them in a cold garage where they will be protected from stiff wind, but still feel cold. If you have no other options, you can just set them outside in a bin, bucket or large container with mulch around their pots and a tarp over them during the coldest days. When the temperature is up over freezing, keep the tarp off so they can get some air and light.

In any event, the basic thing to remember is to keep them around 40 degrees just to be on the safe side and keep them from freezing solid. The temperate carnivores can survive snow and ice, but need a little insulation for their roots.

Keep them hydrated enough so that their soil is moist all winter.

When about 3-4 months is past they will come out of dormancy. This happens naturally outside in Spring weather as it warms up and the days lengthen. Indoors, you can simply get them out of the cold and into room temperatures while providing them 8 hours of light a day with an additonal 2 hours per week until they are back to growing season norms. These plants need a good 3-4 month dormancy to rest each year as they will simply not have the energy to survive a full life span without it.

Christopher