Expert: Sarracenia Northwest - 12/19/2010

Question
Hi there, I have a bunch of sarracenias outdoors, which have done very well outside through the summer months as a result of a good amount of sun and warm temperatures.

I live in England, in zone 8, so usually our winters are just like yours - damp and rainy with temperatures between 0 and 10 degrees C with the occasional cold snap and snow.

This year it has only been cold and snowy so far with widespread frosts, snow and ice. In preparation for the cold snap arriving I decided to be on the careful side by cutting off the majority of leaves and covering my plants in insulation material, wrapping the water trays in black plastic, then  putting them inside one of those 4 tier greenhouses with a plastic cover.

As expected, when the cold temps hit, the water froze and the soil went rock hard. About halfway through the snap I bought all of them inside for a few hours so the soil could defrost and the plants could drink.

When the cold temps were over, the soil had defrosted nicely and I drained away any excess water. But it now is back, and I think it dropped to -11 degrees C last night, and temps are forecasted to be just below zero until Wednesday when the temps rise to around 1.

My worry is that if the soil is going to continually freeze, how are the plants going to be able to drink. Also, will the cold temperatures damage the rhizomes? Finally, should I uncover my plants when the temp rises above around 2, or just leave them covered until spring incase yet another cold period occurs?

Thanks for your help, Chris.

My worry is that

Answer
Hi Chris,

What I use as a decision point here on keeping plants covered is how cold and how long.  If temperatures are going to be below -4 (25F) for more than a night or two, I cover, especially if it is windy.  It temperatures are not expected above freezing, plants definitely get covered.  These kind of conditions are usually when arctic high pressure systems are moving over the area giving cold, dry weather.  I never cover if the weather is going to be wet and cold.  A little snow or just an overnight frost is of no consequence.  They experience these kind of freezing conditions in nature all them time.  North Carolina just a had a spell of weather colder than here in Oregon.

Don't worry about seeing ice in trays, or even pots getting frozen for short periods.  Sarracenia, Flytraps, and most hardy sundews will handle that just fine.

Last year we had some exceptionally cold temperatures with 3 nights right around -14C/7F.  All plants were covered, but we did loose some, and this was very instructive.  The plants that were tender included:  Drosera filiformis "Florida Giant", Drosera filiformis ssp. trayci, Flytraps in exposed pots (stuff in groups well covered was fine), Sarracenia leucophylla "Titan", some Sarracenia minor.  Equally interesting was what didn't have any problems; Sarracenia psittacina (most books and authors say this one is tender; guess it didn't read the book), Sarracenia leucophylla "Tarnok", a large D. binata dichotoma.  At those temperatures everything was frozen solid for a week.

Uncover your plants if the temperatures are going to stay above freezing for a period.  Be sure to spray your plants with a fungicide if they are going to be under cover for a longer period.

Good Growing!

Jeff Dallas
Sarracenia Northwest
http://www.cobraplant.com