Did an inspection of my tree blooms below the barn down the hill after yesterday’s 27 degree freeze. Pears took a bad hit that had bloomed already or middle of blooming. We have a 30ft high pear that always blooms first and it was loaded with them this year. Most of the ones I checked out were fried, along with the smaller pear next to it.
There is a couple more pears about 20ft higher up the hill, a Maxine and Harrow Sweet, the HS had several bad blooms but it looks like it fared better than the others. The Maxine doesn’t have a lot of buds on it and isn’t blooming yet, so those look okay.
Zestar apple which is farthest down the hill is almost in full bloom, there looks to be about half bloom loss from what I could see. Suncrisp next to it not in full bloom, looked a little better, and Macoun better still even tho it’s nowhere close to full bloom.
Pluots look to be fried, no surprise but all the rain we’ve had could’ve helped either. Wild plum bloomed last week and they look wilty.
We have apples up the hill closer to the house and the only with some full blooms, Goldrush, looks okay as well as a Suncrisp.
So, 27 up on the hill meant maybe 25-26 down the hill, and the appropriate carnage took place. We might have been below freezing for maybe 4-5 hours, which apparently was too much.
That tent is an excellent shelter. The thing which would have made all the difference is some sort of decent heat source, which you may want to consider, should you try it again.
If you are close enough to a power source, a small milk house heater would probably be more than enough to heat the enclosure. If you don’t have one of those, a few heat bulbs (the kind which pull 250 watts) would add a lot of heat. Heat bulbs are fairly cheap. They use them in livestock buildings.
Once we needed to protect some new poured concrete from really cold weather in several different pours. We used milk house heaters and heat bulbs to great effect.
If you can’t get power out to your tree, you might consider a small kerosene heater. You may have to fill it up with Kerosene in the middle of the night, but in that enclosure, I bet it would be more than enough to protect your blooms.
There is an Asian Pear orchard and winery near me that has been chronicling their strategy with low temps and blooms on Facebook. Their current thread has some good info.
Thanks for trying to offer some help on this subject. It’s obviously an interest of mine.
I’m always looking for mitigation strategies to minimize freeze damage to fruit buds, flowers and fruitlets, so I checked out their page.
I should probably mention for the sake of accuracy, their mitigation strategies are not based on published data, according to researchers.
Contrary to popular belief, smoke does not hold heat in an orchard setting, according to experts. There is a large apple orchard close to my orchard, and they firmly believe burning round bales helps their temperatures.
But there is evidence that burning round bales, or other large fires (like the brush burned by the orchard mentioned above) actually can make the orchard colder, than it would have otherwise been.
Large fires can “punch” a hole in any natural temperature layer which happens to be holding some heat in, drawing in more colder pockets of air from lower elevations. Sort of like how a chimney draws air in.
If you think about it, it’s exactly the opposite of wind towers used to protect orchards. Wind towers bring air the opposite way, pulling it from above and bringing it down from the inversion layer to warm the orchard. A large fire does the reverse.
The reason smudge pots work is that there are many many small fires scattered throughout the orchard. They don’t “break through” the layer because the heat is not concentrated like a chimney. Plus they give off a lot of radiant heat which substantially helps any trees in the vicinity.
The orchard above did mention their orchard was warmer than some surrounding areas. But that’s not uncommon at all. I have several online local personal weather stations I check during frosty events. They all register quite a variance, depending on elevation and where they place the thermometers.
30 and 32 tonight and tomorrow and then two more in the low 30’s for the upcoming week. Seems to happen every year. A couple of chilly night forecasts turn into 2-3 weeks of November in April. I’ve done some things on the coldest nights, but too busy elsewhere to keep up with days and days. Just gonna have to pray some can make it through.
I’m beginning to solidify my opinion that those critical temp charts are irrelevant if frost is in the forecast. In other words, those charts seem to be right, but are useless if frost will accompany cold temps, which for me they normally do. It’s rare that we get 35 or below and don’t get frost. Case in point the honeycrisp came through the 18 degree night (Monday) without issue, but it was windy - no frost. The following night it got down to 21-22 degrees with a hard frost (no wind) and I lost at least 50%, likely more. The peach orchard in full bloom down the road from me got down to 24 both nights, but since its all hills/ponds in the bottoms (very little frost) they only had a small crop loss. They do nothing to mitigate damage. I’ll be focusing more on frost than temps from here on.
You can calculate frost point with a RH/DP/F simple formula, but I don’t remember what it is. However, for me it’s unnecessary as anything below 35 with less than a 7mph wind will result in frost most of the time. Things like soil temps and water saturation can affect that, but in general it works for me. Plus most of the time weather apps will warn of spring frosts. I have a warning tonight and probably will tomorrow as well.
I’m new here and also new to fruit growing so please feel free to totally discount anything I say but just wanted to throw out what I have planned for my apricots should I get into a freeze situation in my area.
My trees are not large so they can be easily covered. I plan on doing something similar as the tree hut above using umbrella stand and covering that with those emergency mylar blankets (they are cheap $1 each). Here is where things get interesting- I am a chicken and turkey breeder. Chickens and turkeys (as well as their manure) put out alot of heat. I have several small portable chicken coops (used for broody mamas) that I’m figuring I can put under the tree hut with a couple chickens in it which should give off some decent heat overnight and the mylar blankets should keep a good amount of it in. The chickens will be happy to be on fresh ground and plenty of extra yummy treats (mealworms etc) to thank them for their overnight service.
Please note I have not done this yet so I can’t say for sure that it would work but it is my emergency plan and I thought I would share. Maybe someone else having similar resources might consider it. Or maybe it’s just a crazy idea, lol I don’t know but desperate times calls for desperate measures.
This is not true for me. I regularly have killing frosts well before flowering. Just this week I’ve lost half my apple buds at tight cluster due to hard frost. Down to 28 tonight which will kill a bunch more and will likely be headed towards total loss of everything as the forecast now has numerous low 30’s in the ten day. But almost everything survived 18 earlier in the week, but it was too windy for frost. For me frost is the real killer vs. air temp.
I’m not sure how a colder temp with a lower relative humidity is supposed to help flower buds. Frost is simply air at saturation and moisture depositing onto surfaces…ie the frozen form of dew. But as for the cells in the plant, 18° is colder than 24°. If anything, the wind and dry air is more desiccating.
Now a windy cold will have more uniform temps than a radiational cooling night with frost because the atmosphere is well mixed. The calm night will have the coldest air draining into the valleys and hilltops being relatively warmer. Around here you can have nights where the valleys are 10°F colder than the hilltops. Those are the mornings where it’s nice to have your own weather equipment and not have to rely on a station miles away.
Well 33 was forecast for here this morning and we got 30 right before sunrise, so another freeze, but not as bad as earlier in the week. I’ll go inspect things later today. We’re supposed to be 34 tonight, which means another freeze I’m sure.
My jostaberry got zapped pretty good by the freeze on Weds. Think I should prune anything or just let nature take it’s course and let it drop anything it doesn’t need?
It’s not necessarily the formation of frost but the melting of it which is endothermic. This superchills the bud. Frost damage actually happens when it’s warming up.
I think we’ll have to agree to disagree. Yes, melting frost will cause some slight cooling, but by then the ambient is above freezing. I still can’t fathom how that’s worse than frostless teens or low/mid 20s. Of course I don’t have any expertise in plant cell chemistry so maybe I’m missing something. I probably should’ve gone to graduate school for horticulture after meteorology…that would’ve been a nice combo.
I’m with you. Frost isn’t the enemy. It’s the temperature. I’ve been battling spring freezes and reading about it since 1971. I’ve never read about or experienced frost being the damaging factor. The university charts are about temperature, not frost. They know what they’re talking about.
It’s a lot like the idea that covering the tree in ice insulates the flower buds from the cold. That’s not true either.
