Worsleya cold tolerance

Lee Poulsen wpoulsen@pacbell.net
Mon, 08 Dec 2014 17:00:25 PST
I forgot to mention that even though Worsleya grow on bare granite mountain peaks at probably around 1600-2000m a.s.l. (5200-6500 ft), they are completely exposed to the sun all day long (when it's not raining or foggy). So I imagine that because the granite is dark colored, their roots probably experience much higher temperatures than the air temperature. I know the Australians who grow this well say that they can leave their potted Worsleya in full sun even on the hottest days and the plants seem to love it. 

On the other side of the coin, this also means that on the coldest winter nights, if there are no clouds, they will probably experience some pretty good radiation cooling for a few hours. (But not their roots.) So the leaves of mature plants I think can withstand at least several degrees below freezing for a few hours as long as their roots are kept warmer. And they get hardly any rainfall during the coldest months as well.

--Lee Poulsen
Pasadena, California, USA - USDA Zone 10a
Latitude 34°N, Altitude 1150 ft/350 m

On Dec 8, 2014, at 1:41 PM, Lee Poulsen <wpoulsen@pacbell.net> wrote:

> My mature Worsleya has never had any problems with temperatures down to 0°C, or maybe a degree colder than that. (I don't leave my seedlings outside in the winter--they're too valuable to possibly lose.) But remember, it always warms up above freezing during the day in So. Calif. even on the coldest days, and the same is true in this area of Brazil.
> In any case, if you want to kind of see what Worsleyas experience in their native habitat, I finally found actual weather data for the Organ Mountains National Park which is their home (after searching for it for the past 15 years). I plotted the temperature and rainfall data and have uploaded it to the wiki:

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