Loslunas, I lay the pots on its sides. How much this help I have no idea. Sometimes I put a tarp over them & it sure raises the temp.-- the difference inside & outside the tarp was easily felt. This option helped me when we had an artic cold front with wind chill at least in the 22-16*F during 1st week Oct 2009. The leaves were all fried on the first day of the cold winds and after a few hours(2nd day) on putting up the tarp I went & check, it was warm in the enclosure. Most figs were affected except for Hollier, Marseillies VS, Slocan & Tony's Greek.

While the CRFG piece has some good information, some is also of questionable value. The pre-frost sprays would certainly fit into the questionable category. I really don't think many commercial growers are using them.

Also wind chill has no effect on plants at least not in the way it does for warm blooded animals. Wind chill is only a factor for a body that is appreciably warmer than air temperature. Fruit tree buds follow air temperature pretty closely whether the wind is blowing or not. In fact at times, as during a radiation freeze with still winds, bud buds can be colder than air temperature. So if the wind were blowing the buds could actually be warmed by the air. This is part of the effect of running fans during a radiation freeze with an inversion. The fan moves down warm air from above. The warmer air and wind movement warms the buds.

Jose,

Thanks for posting that information. I had seen it before when you posted it sometime back. It a good reminder and very applicable at certain times of the year. Some of these practices are indeed used by me the many Citrus growers in my area. They do work quite well. It is a well kept secret that Louisiana does indeed have a small (compared to Florida and California) Citrus Industry. The taste of Louisiana citrus rivals the fruit that is grown in Florida and California because it has a better sugar to acid ratio. Our farmers did a great job of protecting MANY citrus trees from the unusually cold winter that we had in our area this past season. I lost some but saved most of my citrus from the cold temperatures that we experienced.

Fruitnut......

Wind chill is a function of both AIR temperature and its relative humidity level. And yes indeed, WIND CHILL CAN AFFECT PLANTS. Here is some technical information that I posted in another thread to help explain this multi variable phenomenon.

[This is FYI only and for those other forum members who might want to know some "WHY's" behind potential leaf damage due to cold............it is not just about AIR TEMPERATURE. It is also about wind, leaf temperature, and air humidity level. On a windy night with clear or cloudy skies LEAF temperature will be nearly the same as AIR temperature. However, on a cold, clear night with little to no air movement.....leaf temperature can easily drop 3 to 4 degrees lower than the ambient air temperature. (It can drop as much as 8 degrees in my area.) This is because of the RADIATION heat loss of the fig leaves. The rate of heat loss of those leaves is a function of the air's humidity level. At higher humidity levels often frost will form on those leaves. So, while the ambient AIR temperature might only be 35 degrees F......the actual LEAF temperature might well be 31 to 32 degrees F. That temperature could affect tender new growth.

In my area it is not uncommon for us to see frost form whenever the ambient air temperature is at 40 degrees F or below. This means that the actual leaf temperature reached 32 degrees F or below which froze the dew that condensed on the leaves as the dew point of the humid air was reached during the night. Late Spring frosts can kill fig trees in South Louisiana......especially if the outside air temperature has been cycling through several periods of warmth and cold. Yes, in my area, damaging frosts can form on fig leaves with ambient temperature as high as 40 degrees!! Ask me how I know and what I fear most at this time of year. Potential plant damage is really about leaf temperature and that is a bit harder to measure.]

Dan

Dan:

I know that you know what affects figs in your area. But your explanation did nothing to convince me that wind chill affects plants. In fact you are saying the opposite. You said that leaf temperature can and will drop below air temperature when there is no wind. I agree. But that is exactly the opposite of wind chill as most people think of it. If the wind came up on a cold clear still night, the wind would warm the leaves. That's the opposite of what wind chill does to people and animals.

I'll agree with your last sentence: plant damage is about leaf temperature not air temperature. It's just that in a radiation freeze, wind is your friend, not your foe.

fruitnut,

I agree with you. Wind chill makes temperatures seem even colder than they really are. Animals and humans feel colder because the wind makes moisture on their skin evaporate, removing their body heat. The faster the winds blow the greater the wind chill.....this is due to EVAPORATIVE cooling while what I explained above is due to RADIATION heat loss....entirely different mechanisms.
Thanks for setting me straight.

Dan

Thank you for posting these ideas.

One of the many reasons that I keep my fruit trees pruned to compact size, is that it helps me deal with Mother Nature's challenges. They are small enough that I can cover with nets to avoid birds. Plus, it lets me have more varieties. In addition, I can cover with an old blanket if frost is expected, when the tree is at a sensitive moment.

This may be a reason to prune to bush, instead of tree, shape, although I haven't done that.

I have also used wilt-pruf. It was not a scientific experiment, but it gave me the benefit of thinking I was doing something useful, whether or not it was.

Not for figs, but when my peaches were blooming and a frost was expected, I covered the trees with a blanket, and placed buckets of warm water under the blanket, as you mentioned. Frost on a blooming peach tree can kill it, even if it survives hard freeze when dormant. Seemed to help, or it might have been my imagination.

I've read with interest when others write about having Xmas lights in the tree for warmth. I need to get some at a yard sale, ours are the non-heat twinkly types.

Thanks for the advice.

Daniel

.......posted this in another thread:

Early watering of trees before a night time freeze ABSOLUTELY does give some protection in a "dry" climate or in any area of the country, for that matter, during a period with a low outside relative humidity. I would do exactly what Jose did to INTENTIONALLY increase the relative humidity around my little in ground trees. Water vapor is by far the largest green house gas that we have....man made or other wise....(Al Gore and his Global Warming crowd & our news Media would prefer that you not know this science fact). By increasing the water vapor in the areas around these trees, you WILL effectively trap some of the ground's "radiation" heat around those trees. What is trapped by this added water vapor is some of radiation heat that is quickly lost to the atmosphere after the sun goes down. Ever notice how hot a desert is in the daytime......and then how cold it is at night???? This large variation in temperature occurs simply because there is no humidity (water vapor) in the desert air. If there was some water vapor in the air, the daytime and night time temperatures wouldn't swing as much. If you could somehow increase the relative humidity of the desert air, it simply would not get as cold at night.....nor as hot during the daytime.
I do agree, however, that there is also some good benefits to watering at the time of coldest temperature (closer to sunrise)....due to the latent heat of fusion effects that occur right at the freeing point (melting point) of water as it starts to change from the liquid phase (water) to the solid phase (ice). Too, it is because of this same latent effect that provides protection to fruit trees that have ice already on the branches. Keep the water sprinklers on even when you see ice (or frost) on the leaves and branches and this latent heat will keep the temperature from dropping below 32 deg. F.........that is a warm enough temperature to save a lot of trees from severe damage.

Too, if somehow you can't prevent plain ole frost from forming on your trees (which can easily occur at temperatures as high as 40 deg F in my area)..........get at them with a sprinkler or hose pipe as soon as you see it and you WILL PREVENT some damage. I can get these kinds of "surprise" frosts in my area once in a while when the weather man was a bit off with his forecast.....

Dan

Sorry for the "bump up" but this is always relevant info.

If you use water in Soda bottles, Buckets or Pails then put a piece of Back Plastic in the water.
The sun will warm the plastic and the water will become much warmer than without. I tried and the temp difference is quite high.

snogger,

Don't apologize for bumping this thread up again. It gave me the opportunity to put it in favorites. I am not sure I've seen it before, but if I did, I don't remember it.

Thanks,

noss

In passing: Senninger makes a series of sprinklers called 'wobblers' They are very uniform, and have lots of large drops. They have a standard 1/2 thread. Building your own pole sprinker from PVC pipe and a bucket at the bottom to stabilize is easy. The sprinkler heads are a few bucks each at irrigation supply stores.

Start the sprinkler when it is still +5 C (39 F) as evaporation from the surface of the drops cools the drops. You want to create a film of water on the plant. After a few minutes operation the humidity of the existing water reduces the cooling effect.

Large drops are better, they don't cool off as much in the air.

I'll add a product. Cloud Cover. You can get it on Amazon. It's organic so fine to use on edibles. We live in a micro climate above commercial citrus groves. You know when the temps drop to freezing down there because their wind turbines go on automatically and they are LOUD! That is my clue (along with the weather forcast) to spray all my tropicals and sub tropicals with Cloud Cover.

This winter I sprayed my mango, macadamia, and my caper plant. They all weathered the winter fine and are healthy now. First year for the mango to fruit and fruit is sticking! We don't spray the figs because they never seem to be bothered by our one or two days of freezes.