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"On the other hand, Louisiana has 80 to 100% humidity year round. If you stand outside in La when it's 30F with no wind it will be bone cracking cold with high humidity."

Duuude. Sorry, that is NOT cold. Cold is a week with daytime temps below 20 F, nightime lows at minus (-)10 F (or worse) with no snow and 30 mph winds (which is USDA Zone 4). You simply don't get weather like that in La. which is USDA Zone 7 at its coldest which means the lowest temps are 10-20 F--which I've never heard of in La. Louisiana is simply NOT cold, at least nowhere near as cold as Nebraska.

For what it's worth, humidity generally acts to keep air temperatures HIGHER in the winter. Humidity acts as a sort of blanket in the winter. Look at it like this, you have a bottle of water and a bottle of air. Place both outside when it's below freezing. The bottle with air will become almost instantly the temperature as the surrounding air. The bottle with water will retain heat for alot longer--until it freezes. The water holds the heat better than just air alone. The water lags the temperature. Of course humid air can also take longer to warm up, but if local temps consistently rise above freezing during the day, temperatures will generally stay warmer than colder.

To work this to winter storage advantage to minimize winter kill on stored trees-- keep the roots moist. The water between soil particles freezes before the roots do, protecting them to some extent from freezing. This is the same principle that citrus growers use to protect their orchard fruit from damage during hard freezes. Spray water over the trees and fruit, the frozen water acts as a kind of blanket to protect the fruit beneath.

So, with shallow freezes come in late autumn, like now before I have my trees under protection, I hose them down with water at dusk. The added moisture adds a layer of temporary protection for the roots, at least until things thaw out the next morning.

Frost and freezes in late autumn are actually needed by trees to prepare them for deeper winter dormancy, triggering hormones and chemical changes that "harden" them for the coming winter. I always let all my temperate trees get hit repeatedly with frosts and freezes before I put them under their winter blankets. I never put them under protection before December here in Virginia.

29-Nov-2007	#103
rockm bonsaiTALK ArchMaster Join Date: Oct-2003 Location: Fairfax, Va Country: USA USDA Zone: 7 AHS Heat Zone: ? Posts: 4,561	"On the other hand, Louisiana has 80 to 100% humidity year round. If you stand outside in La when it's 30F with no wind it will be bone cracking cold with high humidity." Duuude. Sorry, that is NOT cold. Cold is a week with daytime temps below 20 F, nightime lows at minus (-)10 F (or worse) with no snow and 30 mph winds (which is USDA Zone 4). You simply don't get weather like that in La. which is USDA Zone 7 at its coldest which means the lowest temps are 10-20 F--which I've never heard of in La. Louisiana is simply NOT cold, at least nowhere near as cold as Nebraska. For what it's worth, humidity generally acts to keep air temperatures HIGHER in the winter. Humidity acts as a sort of blanket in the winter. Look at it like this, you have a bottle of water and a bottle of air. Place both outside when it's below freezing. The bottle with air will become almost instantly the temperature as the surrounding air. The bottle with water will retain heat for alot longer--until it freezes. The water holds the heat better than just air alone. The water lags the temperature. Of course humid air can also take longer to warm up, but if local temps consistently rise above freezing during the day, temperatures will generally stay warmer than colder. To work this to winter storage advantage to minimize winter kill on stored trees-- keep the roots moist. The water between soil particles freezes before the roots do, protecting them to some extent from freezing. This is the same principle that citrus growers use to protect their orchard fruit from damage during hard freezes. Spray water over the trees and fruit, the frozen water acts as a kind of blanket to protect the fruit beneath. So, with shallow freezes come in late autumn, like now before I have my trees under protection, I hose them down with water at dusk. The added moisture adds a layer of temporary protection for the roots, at least until things thaw out the next morning. Frost and freezes in late autumn are actually needed by trees to prepare them for deeper winter dormancy, triggering hormones and chemical changes that "harden" them for the coming winter. I always let all my temperate trees get hit repeatedly with frosts and freezes before I put them under their winter blankets. I never put them under protection before December here in Virginia.