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PALM SOCIETY ARTICLE


Cold Hardiness

Personal experience

By Richard Douglas
Contact Info: PalmGuyWC@aol.com
 
I've been thinking about palm cold hardiness and what to say about it. First, it comes to mind that there is a temp. where a species is damaged, but not killed, and then there is the absolute low that kills a palm. Then there are so many other factors. I move all of my tender things in pots under my overhangs by my patio in the winter. Normally, this is enough to protect even the most tender things. Last year I had two Chamaedorea ernesti-augusti sitting side by side under the overhang. During one of our coldest nights, (About 27 F) one was damaged (about 30% foliage burn), the other was not damaged at all. One thing for sure, if frost can be kept from the foliage of tender things, they will often come through undamaged.

I really think there should be two temperatures mentioned concerning palm cold hardiness. One: at what temp. a palm is damaged, and the other when it is killed. My Parajubaea cocoides will take it to 25 F with no damage, but then it has some overhead protection, but not much. Damage to the tips of the fronds shows below 25 F....and then more so when the temperature drops even lower. The P. cocoides has been subjected to much lower temperatures and has survived. It has been almost completely defoliated 3 or 4 times but has recovered each time.

I had a "hardy" Caryota urens growing here in the ground before the big freeze of 1989/90...Each year it would be slightly, to badly damaged, but would come back in the warmer months. It "bit the dust" in the '89/90 freeze and was the only palm growing in the ground that was killed.

There are so many variables concerning cold hardiness. For one thing, there are the variables concerning the genetic make up of a particular species....some are more hardy than others. Then there are the small micro-climates of our individual gardens. And then, was the palm actively growing in benevolent weather, and then subjected to freezing temp? Was the ground wet or on the dry side?

Another source of damage: Sometimes right after a wet cold front, it will clear and drop below freezing. The water trapped around the emerging leaf spike will freeze and make a "ring" around the emerging frond, while the rest of the fronds are undamaged. This is particularly bad for Rhapis which only put out about 3 or 4 fronds a year for me. One damaged frond can detract from the entire plant......if you are growing them to be specimen plants.

Another marginal palm for me is Brahea Brandegeei, and I agree, below 25 F, expect some foliage damage, however mine survived the freeze of 89/90, but was almost totally defoliated.

It's hard for me to collect my thoughts on cold damage as I have had no bad freezes since 1998, and I think the coldest it's been here in the past 5 years is about 27 F. Normally, I can expect 25 F or below in Walnut Creek in the winter time.

To contact the author of this article, send email to PalmGuyWC@aol.com
 
Originally published in :
PSNCC WEBS
2004-11-26



 
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