We have had success with using several burn barrels to protect orchard fruit. Behind one barrel we positioned an ordinary box fan, and adjacent to another barrel we used a pedestal oscillating fan. Just stuff we already had. The first time we tried this I was skeptical, but we succeeded in saving most fruit, even peaches. We initiated he fire about midnight each night, husband going out hourly, then I took my turn in feeding the barrels until dawn or temperature rise. Orchards near here us gigantic fans, but this low tech use of fans and burning barrels give one confidence for future.
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That’s been used for thousands of years. You have to be careful though. A little wind and you could find your entire orchard on fire. It was also used to control insects and birds in the summer. Insects and birds hate smoke.
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2 counties over there is an olive orchard that has maybe 12 30 foot fans that look like wind turbines. I have been told they are for birds and others say to prevent freeze. I have no idea. They are clearly wired for power.
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I did a similar thing with a central bonfire and a pot of burning coals at the base of each vulnerable tree. I did not see any appreciable benefit.
One year I drove in a circle all night long through four rows with two propane burners strapped to my ATV. That did make a difference but the accelerator got stuck in the cold, I ran into a tree wrapped with burlap and set it on fire. I kid you not.
Last year we added a weather station. I used overhead misters from 34 degrees that night until above freezing along with solar melting the next day. Six low flow high rise misters. One visit to the orchard at the coldest point to make sure they were still functioning properly A much better harvest, but still really poor peach and plum harvest on some trees that were a bit too far away. I missed (no pun,) one cold night in March as I was finishing up my setup and that one may have been what hurt me on stonefruit.
Not gonna happen this year. I’m adding two more sprinklers, I’m going to pull water from a nearby creek with a pump. It’s important to get misters with sufficient reach but not a large volume of water due to possible limb break with weight. Those prolonged freezing temps can last 12 hours out my way.
Alotta work. You bet. Knowing I was doing something and feeling less powerless. Worth it for those few nights.
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There’s a lot of misinformation out there about using sprinklers for freeze protection. Applying too little water can actually cool off the tree, fruit, and buds. It’s called evaporative cooling.
Applying a coat of ice helps nothing. Here’s a professional introduction to the topic:
Using sprinklers to protect plants from spring freezes - MSU Extension
The fans in fields are for frost protection not bird control. They are useful on nights with a strong inversion, ie when air temperature is warmer with increasing elevation. They pull down the warm air to replace the cold air that’s settled near the surface.
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That explains it then. As that location, as well as ours is a bit higher and gets more temperature variance compared to just a few miles away.
I ran it non stop all night. Buds that were blooming came out fine. My issue was that I needed another sprinkler for the size of the orchard. Not all the ice was as clear as I would have liked, but the next morning I was transfixed as I watched the sun start to warm the trees. All the fruit that I saw covered survived.
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The see the strawberry growers in my area apply water over a row cover. It really takes a lot of water and some have posted pictures of them clearing the frozen nozzles all night long on their Facebook page. Seems to work well on strawberries.
A local peach grower used to apply water from frost protection too but the weight of the ice broke a lot of scaffold branches. It took a huge amount of water too which flooded some stuff. I believe he said he used 10 sprinklers per acre and pumped aver 60 GPM. The water helped save a part of his crop but the damage to the trees was so bad he quit.
I have seen lots of pictures of folks burning hay or smudge pots for frost control in order to crack the inversion layer. The tree fruit PDH in my state advised me not to waste my time.
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Just because one throws some water on their trees and ice forms doesn’t mean one saved any fruit. Improperly done under difficult conditions and it not only breaks trees but can increase fruit damage. Fruit often survives temperatures in the 28F range without intervention. So just because you made some ice doesn’t mean you saved anything.
The link above outlines the conditions and requirements for success. From what I’ve heard it’s successfully used in FL because they often have conditions conducive to success. In the rest of the country, it’s seldom used because conditions are often too difficult, ie too windy, dew point too low, temperature too low, etc.
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We used two heat lamps with two box fans last spring on our blueberries during a spring freeze. Seems to have worked.
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That made me laugh out loud. I thought stuff like that only happened to me 
That’s interesting Rick. I had read that you don’t want to crack the layer because by cracking it, any heat produced by the hay or smudge pots would go up through the layer like a chimney? The idea was never to burn big bales for that reason, instead use lots of small fires.
But maybe the idea of cracking the inversion layer is that if the air is warmer on top of the layer, maybe cracking the inversion layer would let the warm air down?
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Anyone spray fish prior to a frost or light freeze? Does it actually help?
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Dad had a bunch of homemade smudge pots he’d use for late frost protection. As I recall, they worked well. A quick Google search showd many available options.
Of course, if climate change is one of your primary worries in life, you should probably look for other solutions
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I’ve not used fish protein. From what I’ve read, cellulose nanocrystals have the most promise. I’m waiting for them to become available commercially.
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@Rosdonald : We can’t know what would have happened if you didn’t do all that spraying. If you got fruit I’d consider it a win.
A lot of the people in our area had no fruit last year. A small commercial operation down the road from me had to buy fruit from Md for their farm stand/tourist farm.
The MSU link above is very good at explaining when the sprinklers are worth it and how much of a difference they can make. I wonder about when the burn barrels and fans are worth it. The same site says a bunch about how and why to move air*. But not specifically how much difference it can make.
I’ve seen the burn barrels in new England. But not here in Va.
- from the msu website - part that talks about Air drainage: “Adding heat by burning creates a rising air column. This is most useful in areas that collect cold air. Heating the cold air causes it to rise, allowing more cold air to flow into the area. The larger the area (five acres minimum) heated, the more efficient this is”
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North Carolina is peculiar…you’re supposed to get a permit for every outdoor burning.
IDK if that applies to a patio firepit or not.
I’m not sure. I had read that small fires in the orchard worked kind of like a wind machine where the warmer air drops through the inversion and helps reduce the frost. I bet enough of them could also raise the air temperature.
We collected small piles of prunings at the end of each row in the Peach orchard a few years ago. We hoped to test the idea of small fires helping with frost but the high winds made it impossible to test. .
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Those are some great pictures! How big was the area covered by a single sprinkler?
This issue is near and dear to me. I am impacted every year by frosts and freezes. I started with sprinklers and that didn’t work very well because our freeze was a plunge to 21f with 15 to 20 mph winds. Not unusual for late March early April. I almost destroyed my trees. Then I shifted to christmas lights, results were worse. If a bulb touched a fruitlet it survived, otherwise a waste of time. The method du jour this year will be covering and heating. I enjoy tree ripened stone fruit so much, I refuse to give up. This approach is ok for a backyard orchard, but likely not fit for commercial growers. I suspect GMO would be one way to get fruits that bloom much later.
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Excellent.
The NC folk are smart…building hoop houses of PVC.
Never have I seen them in any other state.