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What about all the plants that can handle a hard freeze though? Obviously some plants die back to the roots or woody branches during hard freezes and lose their leaves, but a great deal of plants can hold onto their leaves under temperatures of 20F, 10F, even 0F, maybe even -10F, -15F?
For the plants I was referring to where the leaves go limp - they then perk back up once it's warmer. Whether it's a reaction to cold air or cold ground I'm not sure, but I suspect it's cold ground. I've even had it happen with plants like peppers when the soil drops below 45F or so where the leaves get droopy, and they bounce back fine. With the cabbage family plants, it seems to happen with ground freeze/hard freeze but then they usually perk back up again when temperatures get above freezing (even if only 35-45F).
More than likely due to cellular construction or chemical process.
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What is not visible to us from the outside are all the changes at the genetic and cellular level, including some plants’ ability to move water out of cells into the extracellular spaces, where when it freezes, doesn’t do as much damage; or the ability to produce compounds that act like “antifreeze” within the plant.
Our kale, broccoli and some other plants survived about a week during our prolonged first freeze, but now after a month of almost every night being single digits or low to mid teens it's all kaput.
Our kale, broccoli and some other plants survived about a week during our prolonged first freeze, but now after a month of almost every night being single digits or low to mid teens it's all kaput.
Generally, we've still had little to no damage to our frost hardy plants.
Our first hard freeze was Nov 14 (27.5F). That's what fully knocked out my tomatoes, peppers, etc. Prior to that there were a few light freezes (30-32F), but they only did partial damage to my frost tender plants.
So far, we've had 17 nights with freezes, including one period of about 60 continuous hours that didn't get above freezing on Nov 18-21. The coldest freeze was in the high teens.
Collards, tatsoi, mizuna, mustard, bok choy, cilantro, kohlrabi, arugula are still showing zero damage. Some cauliflower is showing a bit of damage on larger outer leaves, same with kale and gai lohn. Basically no damage on broccoli. Maybe very light damage on swiss chard, lettuce and radish leaves. None on turnip and beets. No damage to green onions and parsley either. Peas took moderate damage, and fava beans heavy damage. No damage to parsnip and carrots.
Any damage taken was from either the 60 hours of freeze (got down to low 20s) or the one night it dropped into the high teens.
So far the pattern is similar to last year. Survivability then was still good with short lived ground freezes and freezes into the low 20s or even upper teens, as well as with snow. However, on Jan 1-4, 2022, there was about 60 hours of sub-freezing temperatures, and temperatures going all the way down to the low teens which was too much for many things.
However, inner leaves of parsnip, carrots and turnips survived our winter last year, and mache (aka lamb's lettuce/corns salad) survived undamaged.
I wasn't just referring to vegetables though. Grasses (lawn grass, winter rye, winter wheat), rhododendrons, english ivy, periwinkle, euonymus and more are able to have their leaves survive our winters despite temperatures down to 0F, sometimes even -5F or -10F. Bamboo and akebia that my neighbours grow have their leaves survive down to below 10F. Also plenty of alliums and bulb flowers emerge early enough in spring that they can survive late winter freezes down to 20F, or even 10F in some cases.
Memph and Threerun, just throwing my 2 cents worth in - with regard to your above conversation about damages from freezing I think your respective locations, elevations, soil moisture content and the amount of vapour in the air and the thickness of the air needs to be taken into consideration, not only your temperatures or the types of plants you're growing.
If the air is very dry and crisp plants are more susceptible to damage from freezing much faster than they would be if they were in a location where they're experiencing the same temperature but there is a lot of water vapour and sticky ice crystals floating around in the air. Also, if the elevation at one location (Montana) is quite a bit higher up than the other location (Ontario) the plants at the higher elevation location will always be at greater risk of freeze damage much sooner than other plants that are experiencing the same temperature but at a much lower elevation.
Yes location is something as well. We've had several bouts of high winds- last week we had a squall warning. We were at 40F and calm and literally watched the wall of snow come at us from the west over the Divide. Boom- 50mph winds and blinding snow, temps dropped 30 degrees in an hour.
Haven't followed the conversation so not sure if it was about Turnips or in general but here by the coast everything dies or goes dormant when temperatures go below freezing.
An interesting thing to point out, when leaves don't drop off the trees and the temps go into the 20s, they get stuck on the tree. I think there was a scientific explanation for that but its annoying because it ruins clean up and it weighs down the trees during snowfall.
Haven't followed the conversation so not sure if it was about Turnips or in general but here by the coast everything dies or goes dormant when temperatures go below freezing.
An interesting thing to point out, when leaves don't drop off the trees and the temps go into the 20s, they get stuck on the tree. I think there was a scientific explanation for that but its annoying because it ruins clean up and it weighs down the trees during snowfall.
That's what happened here with one of our Japanese maples. There were still a fair bit of leaves on the tree when the harsh freezes (upper teens/low twenties) hit on the third week of November. Then the leaves just shriveled and stayed on the tree until late November (a handful are still on the tree now).
Weirdly enough, there's a silver maple that still had quite a lot of green leaves on it a week ago in my neighbourhood. Even now, there's a large branch with some yellow-ish green leaves on it that aren't even that shriveled up. Makes me wonder if the house there has a heated driveway or something (with the roots going under the driveway)??
Memph and Threerun, just throwing my 2 cents worth in - with regard to your above conversation about damages from freezing I think your respective locations, elevations, soil moisture content and the amount of vapour in the air and the thickness of the air needs to be taken into consideration, not only your temperatures or the types of plants you're growing.
If the air is very dry and crisp plants are more susceptible to damage from freezing much faster than they would be if they were in a location where they're experiencing the same temperature but there is a lot of water vapour and sticky ice crystals floating around in the air. Also, if the elevation at one location (Montana) is quite a bit higher up than the other location (Ontario) the plants at the higher elevation location will always be at greater risk of freeze damage much sooner than other plants that are experiencing the same temperature but at a much lower elevation.
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There might be some element of that. It does seem like frost sensitive plants like marigolds, tomatoes, tomatillos and peppers are able to survive light freezes here if they're hardened off - this season mine survived three nights in the 29-31F range before finally being taken out by a 28F night. So maybe our low elevation and humidity helps?
But when you have plants like English Ivy and periwinkle where the leaves stay on even during a harsh winter here (-25C), they clearly must have some special adaptation. Same with things like mache - which is especially impressive considering how tender its leaves are. Winter wheat leaves can survive down to -40C or so I believe - leaves included?
Our kale is starting to look a bit beat, but many other brassicas are still in good condition. None of them are growing though of course - that generally necessitates temperatures of at least 10-15C during the day, and we're mostly in the 0-8C range now, with lows around -5C to 5C.
....... But when you have plants like English Ivy and periwinkle where the leaves stay on even during a harsh winter here (-25C), they clearly must have some special adaptation. Same with things like mache - which is especially impressive considering how tender its leaves are. Winter wheat leaves can survive down to -40C or so I believe - leaves included? ......
Yes they do have a very special adaptation. English Ivy and periwinkle (vinca) are perennial evergreens that produce their own antifreeze proteins. Most evergreen plants and trees produce antifreeze proteins. Several varieties of winter rye also produce antifreeze proteins, and while I don't know anything about winter wheat I'll assume it does too. Likewise with mache salad greens (a.k.a. Valerianella locusta - a distant member of the honeysuckle family) which even being considered a tender annual it can stay alive and keep on growing down to 5 degrees F.
In the far northern hemisphere (sub-arctic Canada, Russia, Siberia) there is a species of perennial honeysuckle shrub named Haskap that produces delicious edible berries similar in colour to blueberries and now several cultivars are being cultivated commercially on university farms in Saskatchewan and Oregon. It isn't an evergreen, it's deciduous and drops its leaves in winter but in winter it's roots produce antifreeze proteins that will keep the roots and bare branches alive down to -70 degrees F. I've been experimenting with 6 haskap berry shrubs for the past 5 years now. The berries are elongated and square sided and they taste like a cross between raspberry and blueberry. Jam packed with more anti-oxidants than blueberries.
There are numerous plants and also some animals and fish that produce their own antifreeze proteins.
Yes they do have a very special adaptation. English Ivy and periwinkle (vinca) are perennial evergreens that produce their own antifreeze proteins. Most evergreen plants and trees produce antifreeze proteins. Several varieties of winter rye also produce antifreeze proteins, and while I don't know anything about winter wheat I'll assume it does too. Likewise with mache salad greens (a.k.a. Valerianella locusta - a distant member of the honeysuckle family) which even being considered a tender annual it can stay alive and keep on growing down to 5 degrees F.
In the far northern hemisphere (sub-arctic Canada, Russia, Siberia) there is a species of perennial honeysuckle shrub named Haskap that produces delicious edible berries similar in colour to blueberries and now several cultivars are being cultivated commercially on university farms in Saskatchewan and Oregon. It isn't an evergreen, it's deciduous and drops its leaves in winter but in winter it's roots produce antifreeze proteins that will keep the roots and bare branches alive down to -70 degrees F. I've been experimenting with 6 haskap berry shrubs for the past 5 years now. The berries are elongated and square sided and they taste like a cross between raspberry and blueberry. Jam packed with more anti-oxidants than blueberries.
There are numerous plants and also some animals and fish that produce their own antifreeze proteins.
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Do you know if any brassicas produce anti-freeze proteins? I'm guessing it's more cellular rearrangement for most varieties since they go limp in the cold and don't have the ability to survive extreme cold... but some varieties do have the ability to survive rather cold temperatures.
I'm surprised that my passiflora caerulea still has green leaves with the -8C temperatures we got considering it's native to the subtropics of South America which have very mild winters. My understanding is the leaves can survive to -10C and roots to -15C?
I just perused this- a pretty detailed short article on plants and antifreeze proteins. I’m working on my phone so can only provide the link. Good read
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