Much of the country experienced an extreme cold spell last week. The weather forecasters called it a polar vortex and depending on where you lived, it swept through with a fury between January 5th and 8th.
I’m sure you’ve heard all the meteorological explanations on the news for yourself, but here’s the way Scientific American recaps it:
“The polar vortex is a prevailing wind pattern that circles the Arctic, flowing from west to east all the way around the Earth. It normally keeps extremely cold air bottled up toward the North Pole. Occasionally, though, the vortex weakens, allowing the cold air to pour down across Canada into the U.S., or down into other regions such Eastern Europe.”
During the vortex, the daily temperatures being reported in Minnesota and the Dakotas were truly mind-boggling – 20 to 30 degrees below zero! Where I live in Atlanta, we had a record low of 6 degrees, combined with an extended freeze where it didn’t go about 32F at all for several days, which is unusual here.
For many gardeners, any cold damage sustained by their gardens won’t be apparent until spring. Here in the South, it’s a little more obvious, because we have so many plants that actively grow and bloom all winter. Tender evergreen plants like my gardenia bush and my star jasmine vine (Trachelospermum jasminoides) have been completely defoliated by the cold; in the past the plants were able to recover and put out new leaves in spring. (This is why I try to wait it out and not decide too quickly that a plant should be removed if it appears to be dead.) Pansies and hellebores and camellia bushes all bloom here during the winter, and they typically lose their flowers during periods of extended or extreme cold – the camellia flowers turn to brown mush and drop right off the shrub.
For an interesting point of view, take a look at this blog about kitchen gardening. The blogger/gardener cultivates a winter vegetable garden in the mountains of eastern Kentucky and put a bit of effort into protecting her crop from the polar vortex – with mixed results. She now has first-hand knowledge of the hardiness of the various types of greens she grows.
During the polar vortex, I did not try to cover or otherwise protect any plants for two reasons: I gave that up many years ago and adopted a “no plants that need coddling” approach to gardening. And, I was very, very focused on preventing my pipes from freezing, because some of them are not very well protected at all!
When I first moved to the South I was so enthralled with all the new plants I was discovering that I used to “push zones” – that is, even though I lived in zone 7, I would plant varieties that were known to be hardy only in zone 8 and below. And then I would try to find ways to keep them alive, all the while hoping fervently for a mild winter.
There was, however, one big surprise to emerge from this arctic blast. I’ve written before about my favorite succulent, a pale beauty known as ghost plant (Graptopetalum paraguayense). As I wrote in a previous blog post, all the plant databases state that ghost plant is only winter hardy in zones 9 and 10 (meaning it survives temperatures no lower than 20 to 25 degrees). Even though I’ve been growing it in containers in Atlanta (zone 7) for over nearly 15 years now, I fully expected to lose it this winter – and at this point, I had a lot of it, because it spreads and roots so easily on its own. As a precaution, I brought a couple of small pots of it inside, so I’d have a small stash to propagate from rather than have to search for it in a nursery when spring arrives.
And guess what? It has already warmed up to 60 degrees here in Atlanta, and my ghost plant appears to be okay, no worse for the cold at all. So I don’t know if I somehow ended up with an amazingly hardy strain of Graptopetalum, or if somehow the conventional wisdom about this plant’s hardiness is just all wrong. Here it is, happily spilling out of its pot and cascading down a concrete wall in the sunshine — I took this photo on Saturday, January 11, just two days after the polar vortex blew out of town, and I can’t see any signs of cold damage at all.