Irrigation in cold weather

Lee Poulsen
Fri, 25 Jan 2008 17:15:05 PST
Jane McGary wrote:
> Should I water the plants now, even though they may be exposed to 
> sub-freezing air temperatures at night? Or should I wait a few days until 
> it begins to rain again -- meaning that it will not freeze at night, and 
> the plants won't have bright sun on their foliage? Are they safer in 
> circum-freezing temperatures when a little on the dry side, or when fully 
> hydrated?

Don't know about bulbs or small plants, but with cold-hardy subtropical 
fruit trees (citrus, avocado, etc.) and palms grown in the Zone of 
Denial (USDA Zones 8b/9a), it has been shown during a number of the 
superfreezes in previous decades, that the trees that survived the best 
(or just plain survived) had not been watered and were on the dry side 
just before the freezes hit. What I read about those incidents was the 
hypothesis that the partially dessicated cells had a higher 
concentration of salts in the water that remained in them, which has a 
lower freezing point and thereby kept the cells from being frozen and 
bursting and killing them.

--Lee Poulsen
Pasadena, California, USDA Zone 10a

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