Here are a few more photos from last week's ice storm. Amazingly, all the plants in these photos suffered virtually no damage.
A prickly pear cactus (genus Opuntia, species unknown) in front of the drooping fronds of the not-really-cold-hardy Phoenix canariensis (Canary Island Date Palm).
The escallonia hedge (Escallonia x exoniensis 'Fradesii').
Above: Washingtonia robusta (Mexican fan palm)
Below: Magnolia grandiflora 'D.D. Blanchard' with Schefflera taiwaniana in the foreground.
Finally, in the past few years, I have come up with a simple way to measure the "badness" of an arctic outbreak. It takes into account both temperature and the length of time it has been below freezing. After all, many subtropical plants can take 20 degrees for a few nights, but not 10 degrees for even a few hours. So what is it? It's this fountain:
The photo above was taken on Friday, Jan 20th, 2012. Temperatures had finally risen above freezing after two full days in the 20's. But compare that with the picture below:
Same fountain, but a lot more ice. This was taken in November of 2010 - during the pre-Thanksgiving arctic mess that gave us lows of 15 degrees and kept the high temperatures in the 20's for a couple days. I had over 30 plants die during this outbreak, and many other plants died to the ground (like my escallonia hedge). Once I get a collection of several photos like this, I can assign them a rating and determine how bad a particular arctic outbreak was. Now this is not completely scientific, but it does quantify the severity of an arctic outbreak in a simple way. Perhaps in the future, instead of labeling the minimum temperature of plant labels, we will label the "cold severity number" to give us a better understanding of what conditions (coldness + time) a particular plant might be able to withstand.