Q/A #81 - Careful Not to Overheat Your Flytraps

QUESTION:
I’m very impressed with a Venus Flytrap I got from you, so I ordered a second one. I'm really confused about dormancy. I heard it’s not the temperature that makes them go in the dormancy but it’s the less light. Is that true? I live in Indiana and the winters can get pretty cold single digits. I’m wondering, should I put mine in the fridge? Or I can keep them in the windowsill on the back porch? The temperature will range between 35° and 45°F (2° and 7°C). Would that be OK? Will that keep them in dormancy next winter? 
(Submitted in April 2021.)

RESPONSE BY JEFF DALLAS:
We're at the start of the growing season, so we have a long way to go before you need to worry about dormancy. I normally would have you wait until we're towards the end of the growing season to ask your question. But I decided to answer it now because I'm concerned about your little greenhouse.

Are you using it to protect your plants from thunderstorms and hail? That would be very appropriate since the weather in spring can be very unpredictable and harsh at times. Heavy rain and hail and erode the soil, and that's not fun. If you have this for humidity, however, it's totally not needed. Indiana is also more than humid enough for carnivorous plants. Your humidity is routinely double ours here in Oregon where your plants were grown. 

I recommend always having the zipper doors open. During sunny weather, temperatures could become dangerously high if the doors are sealed shut. Flytraps need full sun, but if they overheat in your greenhouse and die, winter dormancy would be a moot issue! So, always keep the doors wide open. When the weather stabilizes, remove the greenhouse and let your plants grow outside. 

As for dormancy, it is induced by the combination of decreased day length (photoperiod) and cool temperatures. If that back porch you mentioned stays in the 30's and 40's, that's perfect. Refrigerator dormancy is dangerous since they can rot so easily. I only recommend that to folks living in true tropical climates. 

What I would do is leave your plants outside up until the first few frosts in the Fall, then move them to the back porch. I assume there are windows there? During dormancy keep them damp, but not standing in water. A tiny amount of water in a tray is ok, but not more than a 1/4" and any time, and brief dry tray periods are fine. 

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