I’m guessing the weather is going to do my plum thinning for me.
I’l saying a prayer for the rest of you.
Scott
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Good luck everyone! I hope we all make it through with no or minimal losses. It’ll be a stressful night. I’m glad my work day has me exhausted or I might not be able to sleep well knowing my poor plants could be freezing to death.
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Brought most of my figs inside and put some under trees. They have too much growth and this is the third time going in and out. Took me close to two hours to do this. Good Luck everyone!
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Peculiar……………MSN just raised our forecast so it’s staying above freezing.
Ya’ think we can believe them?
Good luck everyone. I have two layers of row cover and a sheet covering my strawberries and a sheet over two of blueberries. I am going to get up at 2 when the rain is forecast to stop and turn the Xmas lights on that I wrapped around those blueberries and between the strawberries. Low of 33 so hoping for the best for the trees.
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Nice explanation of what is about to occur in my backyard…
Radiation Frosts A radiation frost is probably the most common during “cold sensitive” times in
Washington and is the easiest to protect against. Almost all frost protection systems/methods
available today are designed to protect against radiant-type frost/freezes. Radiant frosts occur when
large amounts of clear, dry air move into an area. There is almost no cloud cover at night. During
these times, the plants, soil, and other objects which are warmer than the very cold sky will “radiate”
their own heat back to space and become colder and colder. In fact, the plants cool (radiate)
themselves to the point that they can cause their own damage! The plant tissues which are directly
exposed to the sky become the coldest.
These radiation losses (as much as 1-1.5 million BTU/ac/hr) can cause the buds, blossoms, twigs,
leaves, etc. to become 2-4°F colder than the surrounding air which radiates very little of its heat.
The warmer air then tries to warm the cold plant parts and it also becomes colder. The cold air
settles toward the ground and begins a laminar flow towards lower elevations. This heavier, colder
air moves slowly (“drifts”) down the slope under the influence of gravity (technically called
“katabatic wind”), and collects in low areas or “cold pockets”. This drift can also carry a
considerable amount of heat out of or into (from higher elevation heating activities) an orchard or
vineyard.
The general rate of temperature decrease due to radiative losses can be fairly rapid until the air
approaches the dew point temperature when atmospheric water begins to condense on the colder
plant tissues (which reach atmospheric dew point temperature first because they are colder). The
heat of condensation is directly released at the point of condensation, averting further temperature
decreases (at least temporaily). Thus, the exposed plant parts will generally equal air temperature
when the air generally reaches dew point. At the dew point, the heat released from condensation
replaces the radiative heat losses and further air temperature decreases will be small and occur over
longer time periods. A small fraction of the air will continue to cool well below the general dew
point temperature and drift down slope.
Thus, having a general dew point near or above critical plant temperatures to govern air temperature
drop is important for successful, economical frost protection programs (which is, fortunately, often
the case). Economically and practically, most cold temperature modification systems must rely on
the heat of condensation from the air. This huge latent heat reservoir in the air can provide great
quantities of free heat to an orchard or vineyard. Severe plant damage often occurs when dew points
are below critical plant temperatures because this large, natural heat input is lacking and our other heating sources are unable to compensate. There is little anyone can do to raise dew points of large,
local air masses.
Concurrent with the radiative processes and in the absence of winds, a thermal inversion condition
will develop where the temperature 50 to several hundred feet above the ground may be as much as
a 10-12°F warmer than air in the orchard. Springtime temperature inversions in central Washington
will often have a 3-5°F temperature difference (moderate inversion strength) as measured between
6 and 60 feet above the surface. Many frost protection systems such as wind machines, heaters and
undertree sprinkling rely on this temperature inversion to be effective.
41F with a 14F dew point here… not good. …winds have come way down/skies are clear.
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After supper I went out in a coat and toboggan and put about 6 tarps on the strawberries. I got a big one from down in the barn, plus a few big sheets. So, my patch is about 80% covered, much better coverage than before. Took about an hour to do the job.
The temp at 10pm is 43 uphill/41 down the hill, and has held steady for a few hours. Prob because we have very light (on radar anyways) rain, and clouds. Hope it sticks around for a few more hours, but I know it’ll eventually clear out. I think if it stays above 40 until midnight, we might get just a minimal freeze.
Since most of my tree fruit is already gone, I hope all the berry plants do well. Some rasps (Prelude) are just now blooming, the blacks aren’t, gooseberries have buds on them, but can’t say for sure they’re blooming. They are at the most risk being furthest down the hill. I might go down there and drape a sheet over the big one before bed.
Good luck, especially to those in central and west PA, forecast models are showing some mid 20s for tonight.
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… but the state change from water to ice would yield a lot more, wouldn’t it?
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I put these in because they are supposed to be extremely cold hardy.
We all know that cold hardy means the lowest temp in the dead of winter but the primitive part of my brain refused to consider the “what if”
I try to make myself feel better by telling myself that the lower the lows, the higher the highs feel.
But right now, the low still feels pretty low 
Mike
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Frost and freeze conditions forecast for May 7-9 are expected to damage unprotected fruit crops and other sensitive vegetation. If winds are light and insufficient for air mixing to prevent an inversion freeze, running frost fans in orchards may be necessary to prevent damage to apple trees at pink or bloom. Orchards at pink are at a greater risk of crop injury whereas those still at tight cluster should fare better. Critical temperatures for fruit damage to trees at tight cluster are 27°F for a 10% bud kill, and 21°F for a 90% bud kill. If bud growth has reached pink, 28°F will result in a 10% kill and 24°F will result in a 90% kill (information provided by the IPM Institute of North America and UW-Madison). A recent Michigan State University article outlines strategies for protecting fruit crops: What can fruit growers do if a freeze is coming? - Fruit & Nuts.
Wisconsin Pest Bulletin — Fruits
Volume 65 Number 2 Date 05/07/2020
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Yeah…if it froze…? might just get a layer of ice on the top of the bucket. Maybe the key is to have an island on the middle of a lake or river…then that can act as a freeze buffer. Lots of islands up here on the Mississippi…i just need to declare one my own…
33F/18F at 1am…yikes…off to bed. Good luck trees.
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Well, I’m off to bed, but with an update. As mentioned earlier, the temps were hovering around 41 from like 9pm until midnight, because we had a light rain and clouds. I’m thinking it may not get that cold after all.
Before calling it a night, I thought I’d better go cover my big gooseberry plant that had a bunch of fruit buds opening on it. This was at about 1:15, so I pulled on my coat, hat and gloves and headed out the door. It was then about 39 up here on the hill. The moon was out, with wispy clouds passing by it, and little wind.
I went to the barn to get some stakes to hold up my covering, and went down the hill to place a sheet and tablecloth over the bush. It took me about 10 minutes to get it done by a spotlight. I was thinking, “this is probably overkill, but I don’t want to take a chance”.
I went back up the hill and looked up to the sky and saw the moon, stars and now, no clouds. The front had clearly pushed through. You could tell it was colder.
I got the temp sensor off my deck and placed it in the strawberry patch to get a more accurate reading there. I also have another sensor down in the barn at ground level.
To my shock, when I walked back into the house (about 2am), it was already 35 in the patch and down the hill. So, in about half an hour it dropped about 5 degrees, and wasn’t stopping there. I said you gotta be kidding me, along with some expletives. I went to take a shower before bed, and just checked them again, and they’re both sitting at 32, with about four more hours of dark left.
This is crazy, May 9th, and our second freeze in three days, but this one could be worse. I dread getting up later and seeing what has happened, it’s really disappointing to say the least. Maybe it’ll find a bottom and not drop much more, but right now I don’t have a good feeling. Forecast low is 27, so we’ll see. As I close it’s about 31.
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Forecast now is calling for at least frost again on Monday morn.
We are sitting this morning at -2 C but it looks like it may not have gone past -3C. I haven’t looked yet.
We fully wrapped the Asian pear since it’s buds were showing colour and we’re only able to do one pear. I chose the lucious since it has been the producer so far.
Tried the apricot but it’s a bit too big.
Babies were all soaked and moved inside.
I took all the asparagus tips and they were tasty.
Cut a chunk of the rhubarb, mostly the biggest leaved ones, and then layered the cut leaves over the rest. I figured it was worth a try. They are very sheltered.
Haskap bed was too big to do anything so it’s all about hopping the Siberian genes do their job with those.
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It was definitely late frost last night. I am gladed I moved all the pots indoor. Not sure how the peaches and large persimmon
trees are holding up .
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33.1F here was the lowest, looks like I will be OK this round…
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Did you use the blow torch at all? We may get another frost on Sunday morning. Ugh. I did covered my leafed it out apple grafts with the hair nets.
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No… the alarm didn’t go off, not sure why but it might need to be below the temp for a full hour.
@BobC: ouch.
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