Does Sub-15 Degrees at the Roots Kill Trees?

[Leo in N E Illinois]

Shit.. Had to look that up. That is not just cold. That is freezing off all extremities cold!

There are parts of the Midwest USA that are as cold as Siberia. Way back when I was a young wet behind the ears chemist, in 1982, I was sent to Rhinelander Wisconsin, in January 81? maybe 82?. There was a problem with the lignin liquor our company was buying from Lake States Paper in Rhinelander. There was what today would have been called a polar vortex. The real temperature, without wind chill got down to -44 F at night during that trip. That is impossibly cold, -44 F = -42 C, it was so that cold breathing was difficult. When possible, you never turn your car off, because if the engine cools, it will never start again. Outside the motel is a whole parking lot full of cars idling all night long.

The team leader of our group had the bright idea of going bar hoping that night, through rural Wisconsin, in -44 F. I was young enough (early 20's) and dumb enough that I happily went along. The night ended in a biker bar some 40 miles into the northwoods outside of Rhinelander. Fortunately we had a New Jersey biker with us (yes, some NJ bikers grew up to be chemists). It was a weird scene out of Sons of Anarchy set in Wisconsin. No guns flashed in anger, but it was Wisconsin, one bar tender showed us his gun collection, a patron or two clearly had guns tucked not so discretely in their belts. Nobody cared, it was rural Wisconsin. We all lived, had a great laugh. No serious frostbite. We solved the problem, had to switch to sourcing our lignin liquor from Bellingham, Washington, which definitely contributed to the Lake States mill going out of business. By solve the problem, I mean, we realized the Lake States mill had no control of the chemistry of their pulping process. It was clear they had stopped investing in optimizing the process. The decision to shut down had likely already been made. The lignin we bought was a waste product from the kraft paper process. Lignin is a waste in making paper, but a very useful feed stock for other industries. The paper mills that are still in business today understand this. We were buying lignin as a wetting agent for modifying the wetting and set up of concrete.

Rural northwestern Illinois, northern Iowa, Minnesota, N & S Dakota, Wisconsin, Upper Peninsula Michigan and central northern Michigan can get brutally cold. These are the areas that were USDA zone 4 and zone 3 before maps were revised 10 years ago. Average cold would not be that bad, but the occasional outbreak would be brutal.

Thankfully, the one good thing about climate change is that this sort of brutal cold is less and less likely. I have lived more or less within 50 miles of my birthplace most of my 67 years. At one time -20 F was common at least once or twice every winter. No longer. Now the common winter low is about -10 F. which is about -23 C. And it seems that this is even less likely. So who knows. Maybe I'll be able to plant palm trees in my yard the next time I update my landscaping. I had a friend who had a collection of palms hardy in Charlotte NC, so there are some that take some frost.

 

[Dav4]

There are parts of the Midwest USA that are as cold as Siberia. Way back when I was a young wet behind the ears chemist, in 1982, I was sent to Rhinelander Wisconsin, in January 81? maybe 82?. There was a problem with the lignin liquor our company was buying from Lake States Paper in Rhinelander. There was what today would have been called a polar vortex. The real temperature, without wind chill got down to -44 F at night during that trip. That is impossibly cold, -44 F = -42 C, it was so that cold breathing was difficult. When possible, you never turn your car off, because if the engine cools, it will never start again. Outside the motel is a whole parking lot full of cars idling all night long.

The team leader of our group had the bright idea of going bar hoping that night, through rural Wisconsin, in -44 F. I was young enough (early 20's) and dumb enough that I happily went along. The night ended in a biker bar some 40 miles into the northwoods outside of Rhinelander. Fortunately we had a New Jersey biker with us (yes, some NJ bikers grew up to be chemists). It was a weird scene out of Sons of Anarchy set in Wisconsin. No guns flashed in anger, but it was Wisconsin, one bar tender showed us his gun collection, a patron or two clearly had guns tucked not so discretely in their belts. Nobody cared, it was rural Wisconsin. We all lived, had a great laugh. No serious frostbite. We solved the problem, had to switch to sourcing our lignin liquor from Bellingham, Washington, which definitely contributed to the Lake States mill going out of business. By solve the problem, I mean, we realized the Lake States mill had no control of the chemistry of their pulping process. It was clear they had stopped investing in optimizing the process. The decision to shut down had likely already been made. The lignin we bought was a waste product from the kraft paper process. Lignin is a waste in making paper, but a very useful feed stock for other industries. The paper mills that are still in business today understand this. We were buying lignin as a wetting agent for modifying the wetting and set up of concrete.

Rural northwestern Illinois, northern Iowa, Minnesota, N & S Dakota, Wisconsin, Upper Peninsula Michigan and central northern Michigan can get brutally cold. These are the areas that were USDA zone 4 and zone 3 before maps were revised 10 years ago. Average cold would not be that bad, but the occasional outbreak would be brutal.

Thankfully, the one good thing about climate change is that this sort of brutal cold is less and less likely. I have lived more or less within 50 miles of my birthplace most of my 67 years. At one time -20 F was common at least once or twice every winter. No longer. Now the common winter low is about -10 F. which is about -23 C. And it seems that this is even less likely. So who knows. Maybe I'll be able to plant palm trees in my yard the next time I update my landscaping. I had a friend who had a collection of palms hardy in Charlotte NC, so there are some that take some frost.

There are palm trees planted in the subdivision I lived in for 12 years in N GA, zone 7b. It fell to 4 F the 3rd winter we were there... palm tree was fine and still is the last time I saw it a few months ago. Not sure about planting in your yard but you could definitely keep one in your well house... .

 

[Frozentreehugger]

I live usda zone 4 Canada . That means sustained temp below -15c basically month of jan and Feb with possibility of below -25 c that’s 5 f to -15f so colder than most or all you guys . My experience is this . Cold hardy trees where they experience bellow freezing in nature . In general when young there roots are shallow so they freeze solid . And have some ability to survive water freezing in there cells . Normally they get covered in snow for the worst of winter . As mentioned here snow is a great insulator . Remember insulation slows the transfer of heat not stops it . So yes placing trees on the ground to take advantage of ground heat and mulching and burying in snow can all help . As the native tree matures so it is now above the snow it also has roots below the frost so access to water . This is the primary reason plants in a pot reduce the cold hardy east of a tree . In a pot they freeze all the roots no access to water . I read once in freezing zones a plant in a pot is one zone less in hardy then in the wild ie a zone 4 tree becomes a zone 5 tree makes sense to me . So some hard learned experience . When the roots are frozen and have no water access they need protection from wind . PERIOD no matter Deciduous or conifer snow is insulator like bonsai soil has a lot of air spaces snow melts and freezes into water . Frozen water touching plant materiel can be harmful even kill cold hardy trees . The drying wind is DEADLY . All species temp fluctuations especially above and below freezing thawing and refreezing root balls is harmful like Sorce I have wintered trees on a 20 floor balcony at one time . My winter storage is this all hardy trees slowed to freeze there root balls on benches . When there solid I leave then as long as I dare in the light place then on the ground briefly . They go in a unheated non attached insulated building with no light . Including conifers . In spring I prolong them there . Taking steps to not disturb them ie open door and let warmth in . Until I’m confident when they come out they will thaw out and stay thawed . This has achieved the best results . Fir me I have successfully over wintered zone 5 plants in zone 4 all other attempts have had some failure even zone 3 plants buried beside foundation and mulch and snow . In this area we had normal winter temp but lower snowfall then normal worse a mid winter thaw melted a lot of snow . There is landscape plants everywhere this spring that everything above the snow is brown dead . I believe all trees would benefit from winter light but if the root ball is froze and there is no light they they stay dormant . The nursery business freezes seedlings with no light all the time . Freeze thaw is bad frozen tree in the wind is bad water froze around living tissue is bad roots above freezing plant needs water and light The cold is not all bad . Some trees need and thrive in the cold. . Apple is a good example cold climate tree . Orchard growers will tell you they worry about warm winters here . General belief is they need to freeze solid for 40 days straight to get best yield . As a bonsai some cultivars may need more protection but I have seen the experiment . A tree in a greenhouse un frozen grows weakly next spring frozen tree explodes to life . The cold also is a natural bug and disease killer . Sorry this is so long just feel it’s important subject after all dead trees in spring is a huge bummer hope this helps some of you to show what the worst danger is in extreme cold

 

[Frozentreehugger]

I should add age and state of refinement. . Is a player just like a old tree in the wild needs longer to recover when collected . A tree in refinement where you have taken steps to slow down its growth ( and vitality ) . I believe needs or is safer in better winter protection than say the well feed vigorously growing young tree in development

 

[August44]

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I live usda zone 4 Canada . That means sustained temp below -15c basically month of jan and Feb with possibility of below -25 c that’s 5 f to -15f so colder than most or all you guys . My experience is this . Cold hardy trees where they experience bellow freezing in nature . In general when young there roots are shallow so they freeze solid . And have some ability to survive water freezing in there cells . Normally they get covered in snow for the worst of winter . As mentioned here snow is a great insulator . Remember insulation slows the transfer of heat not stops it . So yes placing trees on the ground to take advantage of ground heat and mulching and burying in snow can all help . As the native tree matures so it is now above the snow it also has roots below the frost so access to water . This is the primary reason plants in a pot reduce the cold hardy east of a tree . In a pot they freeze all the roots no access to water . I read once in freezing zones a plant in a pot is one zone less in hardy then in the wild ie a zone 4 tree

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becomes a zone 5 tree makes sense to me . So some hard learned experience . When the roots are frozen and have no water access they need protection from wind . PERIOD no matter Deciduous or conifer snow is insulator like bonsai soil has a lot of air spaces snow melts and freezes into water . Frozen water touching plant materiel can be harmful even kill cold hardy trees . The drying wind is DEADLY . All species temp fluctuations especially above and below freezing thawing and refreezing root balls is harmful like Sorce I have wintered trees on a 20 floor balcony at one time . My winter storage is this all hardy trees slowed to freeze there root balls on benches . When there solid I leave then as long as I dare in the light place then on the ground briefly . They go in a unheated non attached insulated building with no light . Including conifers . In spring I prolong them there . Taking steps to not disturb them ie open door and let warmth in . Until I’m confident when they come out they will thaw out and stay thawed . This has achieved the best results . Fir me I have successfully over wintered zone 5 plants in zone 4 all other attempts have had some failure even zone 3 plants buried beside foundation and mulch and snow . In this area we had normal winter temp but lower snowfall then normal worse a mid winter thaw melted a lot of snow . There is landscape plants everywhere this spring that everything above the snow is brown dead . I believe all trees would benefit from winter light but if the root ball is froze and there is no light they they stay dormant . The nursery business freezes seedlings with no light all the time . Freeze thaw is bad frozen tree in the wind is bad water froze around living tissue is bad roots above freezing plant needs water and light The cold is not all bad . Some trees need and thrive in the cold. . Apple is a good example cold climate tree . Orchard growers will tell you they worry about warm winters here . General belief is they need to freeze solid for 40 days straight to get best yield . As a bonsai some cultivars may need more protection but I have seen the experiment . A tree in a greenhouse un frozen grows weakly next spring frozen tree explodes to life . The cold also is a natural bug and disease killer . Sorry this is so long just feel it’s important subject after all dead trees in spring is a huge bummer hope this helps some of you to show what the worst danger is in extreme cold

I live usda zone 4 Canada . That means sustained temp below -15c basically month of jan and Feb with possibility of below -25 c that’s 5 f to -15f so colder than most or all you guys . My experience is this . Cold hardy trees where they experience bellow freezing in nature . In general when young there roots are shallow so they freeze solid . And have some ability to survive water freezing in there cells . Normally they get covered in snow for the worst of winter . As mentioned here snow is a great insulator . Remember insulation slows the transfer of heat not stops it . So yes placing trees on the ground to take advantage of ground heat and mulching and burying in snow can all help . As the native tree matures so it is now above the snow it also has roots below the frost so access to water . This is the primary reason plants in a pot reduce the cold hardy east of a tree . In a pot they freeze all the roots no access to water . I read once in freezing zones a plant in a pot is one zone less in hardy then in the wild ie a zone 4 tree becomes a zone 5 tree makes sense to me . So some hard learned experience . When the roots are frozen and have no water access they need protection from wind . PERIOD no matter Deciduous or conifer snow is insulator like bonsai soil has a lot of air spaces snow melts and freezes into water . Frozen water touching plant materiel can be harmful even kill cold hardy trees .Drying wind is DEADLY . All species temp fluctuations especially above and below freezing thawing and refreezing root balls is harmful like Sorce I have wintered trees on a 20 floor balcony at one time . My winter storage is this all hardy trees slowed to freeze there root balls on benches . When there solid I leave then as long as I dare in the light place then on the ground briefly . They go in a unheated non attached insulated building with no light . Including conifers . In spring I prolong them there . Taking steps to not disturb them ie open door and let warmth in . Until I’m confident when they come out they will thaw out and stay thawed . This has achieved the best results . Fir me I have successfully over wintered zone 5 plants in zone 4 all other attempts have had some failure even zone 3 plants buried beside foundation and mulch and snow . In this area we had normal winter temp but lower snowfall then normal worse a mid winter thaw melted a lot of snow . There is landscape plants everywhere this spring that everything above the snow is brown dead . I believe all trees would benefit from winter light but if the root ball is froze and there is no light they they stay dormant . The nursery business freezes seedlings with no light all the time .Freeze thaw is bad frozen tree in the wind is bad water froze around living tissue is bad roots above freezing plant needs water and light. The cold is not all bad . Some trees need and thrive in the cold. . Apple is a good example cold climate tree . Orchard growers will tell you they worry about warm winters here . General belief is they need to freeze solid for 40 days straight to get best yield . As a bonsai some cultivars may need more protection but I have seen the experiment . A tree in a greenhouse un frozen grows weakly next spring frozen tree explodes to life . The cold also is a natural bug and disease killer . Sorry this is so long just feel it’s important subject after all dead trees in spring is a huge bummer hope this helps some of you to show what the worst danger is in extreme cold

Not at all sure I agree with you when you say, " A tree in a greenhouse unfrozen grows weakly next spring frozen tree explodes to life". Where did you come up with that? I was of the opinion that certain trees need dormancy to do well. Dormancy has to do with periods of day light, air temperatures (up or down), and maybe water to the roots. I understand that these trees need to be in a dormant condition for a period of time, but I have not heard that they need to be frozen solid. There are a lot of trees that need dormancy with temps 35-45 degrees F for 1-4 months. If you freeze some of these trees they dead!

I would agree that if you keep a tree that needs dormancy as mentioned above in temps that are above that dormancy requirement, then you will have a problem, but I understood that the problem would occur if you did it two years in a row. Maybe all BS.

 

[Frozentreehugger]

Not at all sure I agree with you when you say, " A tree in a greenhouse unfrozen grows weakly next spring frozen tree explodes to life". Where did you come up with that? I was of the opinion that certain trees need dormancy to do well. Dormancy has to do with periods of day light, air temperatures (up or down), and maybe water to the roots. I understand that these trees need to be in a dormant condition for a period of time, but I have not heard that they need to be frozen solid. There are a lot of trees that need dormancy with temps 35-45 degrees F for 1-4 months. If you freeze some of these trees they dead!

I would agree that if you keep a tree that needs dormancy as mentioned above in temps that are above that dormancy requirement, then you will have a problem, but I understood that the problem would occur if you did it two years in a row. Maybe all BS.

My statement was in reference to apple not all trees and probable not even all cultivated apples . I’m sure there have been some specifically. Cultured for warmer climates . After all mankind has been playing with them a long time . I may be wrong it’s been awhile but I believe the 40 days of frozen was from Nick Lenz . And like I said warm winters can hurt orchard production . My point was just as some trees will suffer in the cold . Out of there native range so to speak . So will trees suffer that need cold for dormancy . That is all I was trying to say with that example of apple . Trees have had a long history of adapting to a climate . We can’t expect to grow them successfully to far outside there needs .

 

[ShadyStump]

And like I said warm winters can hurt orchard production .

My experience and learning with apples in the ground, and reasonably applied to other trees as well, is that a minimum number of hours below 40F, and for some trees below freezing, are required for optimal dormancy.
It's like the difference between a full 8+ hours of sleep vs a series of short naps throughout the day: napping is better than nothing, but not good enough. An apple tree in an orchard during a mild winter may not keep full, 100% dormancy, so is still expending energy even though it appears dormant.

If you've all read this entire thread, somewhere somebody posted a spreadsheet of maximum temperatures below freezing the roots for a variety of trees can withstand, all based on tests.
Bottom line, all temperate climate deciduous require a dormancy period for optimal health, but what counts can be different for different species.

 

[Potawatomi13]

Personally have seen my trees die from frozen roots once growth begins. Late Spring weather in teens to low 20s exceedingly bad. One was young JBP.

 

[A. Gorilla]

One was young JBP.

Of course it was.

 

[Frozentreehugger]

Personally have seen my trees die from frozen roots once growth begins. Late Spring weather in teens to low 20s exceedingly bad. One was young JBP.

That’s partly my point . I could grow JBP here and some do . But I don’t see the point up here it’s far out of its native needs . I would have to provide better protection in winter . And to many don’t consider things like full sun here is a lot different than full sun in California . I would be lucky to get 1.2 the growth a year they get . Same as a cold weather tree would suffer in the heat there . I grow what fits my climate and conditions . I might push it a bit for something I really like but you need trees to thrive not just grow for bonsai to be successful