Leo in N E Illinois
The Professor
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- 11,337
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- USDA Zone
- 5b
I'm in the northern burbs of Chicago, or the southern burbs of Milwaukee. About as many local neighbors work in Wisconsin as work in Illinois. I'm just a few miles south of where the Illinois-Wisconsin border meets Lake Michigan, a little less than 2 miles from the Lake.
This winter 2018-2019 we had serious cold, at least one night reached -23 F which is roughly -31 C, serious cold, but that came with good snow cover. We had a total of 10 or more nights well below zero F, below -18 C. During these episodes, sometimes there was snow cover, sometimes no snow cover. Our last frost is typically sometime around May 15, though sometimes as early as May 1 can be our last frost. Leaves on the landscape trees are just budding out. Forsythia and Redbud are just starting. We average about 100 to 120 growing days between first and last frost. The farm, 9 miles east of South Haven Michigan had nearly identical cold this winter, and about 18 inches, or half a meter more snow than my home in Illinois, but otherwise it was very similar.
So I hate schlepping trees in and out of my preferred winter shelter, and have been experimenting with just leaving trees lay out for the winter. I do take trees off the benches, and set them on the ground. But that is about it. On the ground they do get some thermal buffering from the soil below, and I do group them a bit which gives some wind protection, but largely they all spend the winter pretty exposed. And they do get some sun in winter. I used to think winter sun was the ''boogeyman'', but I have found it is not as big a deal as I thought. I tend to do this only with trees in larger pots, usually gallon larger nursery pots and or Anderson flats. I have found that even ''good'' meaning ''expensive'' bonsai pottery that is advertised as freeze-thaw resistant is often not freeze-thaw resistant. So trees in ''good'' pots get protected in my well house for the winter.
So here are some trees that have done well this winter.
Pinus banksiana - Jack Pines, my 2 in Anderson flats look great, I have a number of seedlings in mesh walled 'Sorce Pots' (@sorce ) and in 4 inch plastic pots. Some of these were left on their benches all winter, the Anderson flats and the majority were set on the ground. All have greened up and new buds are growing this spring. No losses. Jack pines are definitely the most winter hardy pine I know of. 5th year of wintering without protection 100% hardy. In theory hardy through zone 3 - do try them if you are in the northern tier of states. They might not do well in zone 7 or warmer, but in zone 7 you can leave JBP outdoors all winter, so you don't need Jack pine.
Chamaecyparis obtusa - Hinoki - I used to winter these in the well house, thinking Japan is more like St Louis than Chicago. This is the 3rd year I've left Hinoki out on the ground in an Anderson flat, and no problems. I'd say 100% hardy, but do take it off the bench and set it on the ground for winter.
Pinus bungeana - Chinese Lacebark Pines - I have starting 4th year seedlings, some in an Anderson flat and some in individual 4 inch pots. All spent the winter on the ground and no losses, this is 2 winters in a row. First winter after seed sprouted I did move the flats into the well house. I believe this pine will prove winter hardy in containers throughout zone 5. (@Owen Reich )
Celastrus sp. I think C. orbiculatus - Oriental bittersweet - It could be C. scandens, I have not checked. In gallon containers and 4 inch pots, perfectly winter hardy.
Amelanchier x grandiflora - Service berry - have 2 that have never missed a beat, flower buds are just starting to show. This is an underrated member of the apple family, really nice early spring flowers before leaves fully expand. 100% winter hardy.
Tsuga canadensis - I have one in a 5 gallon nursery pot and a batch of 5 seedlings, about 5 years old in an Anderson flat. The Anderson flat stays on its bench, fully exposed all winter, the nursery pot is on the ground - 100% hardy, no sign of any distress.
Acer ginnala - Amur Maple - I have 2, one in a 5 inch pot, one in a 3 gallon pot. Both are more than 5 years old, never wintered anywhere but outside, on the ground. 100% winter hardy.
Malus hybrid - a crab apple, - don't remember which, one of the weeping crap varieties. I bud grafted onto apple understock some years ago when trying to learn grafting. Both pots on the ground, no protection, flower buds are starting to show. 100% hardy.
Pinus ponderosa - Ponderosa pine - I moved these to Michigan because the back yard was getting to shady. Wintered in full sun, just set on the ground. Looking fabulous, healthier than they every looked in my too shady back yard. These really need full sun to stay healthy, sun in winter is no problem.
Picea engelmannii and pungens - Engelmann spruce and Colorado blue spruce - All did well, full sun, just set on the ground. I have a weeping cultivar of engelmann spruce, and one weeper of Colorado blue spruce, also have grafted varieties of blue spruce, all do fine with no protection.
Picea glauca var densata and Picea orientalis and Picea omorika - all do well juet set on the ground and no extra protection.
Wisteria macrostachya - in a 4 inch diameter pot - just set on ground - did fine.
Chionanthus virginicus - American Fringe tree - has done well 2 winters in a row, both specimens are in 5 gallon and 20 gallon pots. - 3 winters and no problems.
Vaccinium corymbosum - blueberries - select cultivars of highbush blueberries - I have explants from tissue culture and various cuttings sizing up to get them big enough that ''the kid'' can see them from the driver seat of the tractor, so he don't mow them over. Will get planted in the field when about 1 gallon size. These all winter in flats, on the ground. No problems at all.
Carpinus caroliniana - Hornbeam - collected one from the farm, does fine in a cut down nursery pot, set on the ground.
Ostrya virginiana - Hop flowered hornbeam - perfectly hardy even in small 3 and 4 inch pots.
Lycium barbarum - goji berry - One gallon container - set on ground - perfectly hardy 2 winters in a row.
Junipers - virginiana, horizontalis - blue rug, shimpaku, itoigawa, & kiushu, - all in various containers, no winter problems at all. The blue rug, J horizontalis got left on top of the bench and had no problems. All perfectly winter hardy.
Metasequoia - Dawn Redwoods - these are outstandingly hardy. I have left them on the ground and on the bench, and all have survived no problems 3 winters. These are much hardier than bald cypress.
Elms - Ulmus pumila - Siberian elm - left outside, no problems, no protection fully exposed. I have not tested Seiju elm yet. It is supposed to be hardy enough.
Parthenocissus quinquefolia - Virginia creeper - this is another amazingly hardy vine, I leave it fully exposed, just set on the ground in winter.
Chaenomeles hybrids -Japanese Flowering quinces - I have the varieties 'Contorted White', 'Iwai Nishiki' and what I believe is 'Minerva' and these get left out all winter. Just set on the ground. they do fine. These are all larger leaf, larger tunks, more robust types. 'Chojubai', 'Kan Toyo' & 'Hime' need protection, these are small leaf types, and seem to be less hardy in a pot. They might be okay in the ground, but in a pot they need protection. So Chaenomeles, are a some can take it, some can not.
**********************************************************************
Failures - or trees I feel I must protect
Ginkgo - for what ever reason, ginkgo are hardy when planted in the ground as landscape trees, but as a tree in a pot I have had no success wintering them on the ground, or on the bench. I bring my ginkgos into the well house. NOT Reliably WINTER HARDY in 5b
Beech - Fagus - I bring these into the well house, have lost all that wintered unprotected. Even though winter hardy in landscape, they seem to be a problem in a pot.
Japanese Black Pine - Pinus thunbergii - in theory they look like they could be hardy in zone 5, in practice they are not. They might survive one or two winters, but usually within 5 years one winter or another will wipe them out. Also, given my micro-climate, JBP do not wake up on time in spring, because I have cool spring weather. They need heat to ''wake up'' - this means they get short changed on length of growing season. This means that many years my JBP can not be treated as 2 flush pines, they barely have time for one flush of growth. JBP are problematic. Especially since my only JBP experience is the cork bark varieties, I don't grow the normal type.
Satsuki azalea - I love them, love the flowers, they are not hardy here. They do well in cold dark storage for the winter, no unusual leaf drop or any reduction in blooming. Well house is mandatory for them. Zone 7, maybe 6b, no need to test them in zone 5.
Taxodium distichum - Bald Cypress - in the landscape these are perfectly hardy, but in pots are marginal. Had them survive some winters, and fail other winters. Have taken to wintering them in the well house. Must be protected in zone 5
Bamboo - Phyllostachys atrovaginata, aureosulcata, Pleioblastus viridistriatus, and Indocalamus latifolius - all 4 species are perfectly hardy when planted in the ground in the landscape - but planted in pots are not quite winter hardy. Must protect bamboo in winter if in pots. Also include Phyllostachys nigra, black bamboo - which is not winter hardy much north of zone 7.
Japanese Maples, - Acer palmatum - need protection. even though hardy in the landscape.
So that is my ''report''
I post this because I hear of many are going through great lengths to protect trees in winter that are species that are more than winter hardy enough. The great thing about leaving them lay out all winter is you never have to do the ''in and out'' dance with them. My back aches at the thought of running around moving trees just before dark to avoid the frost. I refuse to do it. I am just now beginning to empty my well house, most of my local buddies have been doing the dance with their trees for several weeks now.
So get brave, if you have any of the trees on the winter hardy list, don't baby them, just set them on the ground for the winter. It will save your back in the long run.
This winter 2018-2019 we had serious cold, at least one night reached -23 F which is roughly -31 C, serious cold, but that came with good snow cover. We had a total of 10 or more nights well below zero F, below -18 C. During these episodes, sometimes there was snow cover, sometimes no snow cover. Our last frost is typically sometime around May 15, though sometimes as early as May 1 can be our last frost. Leaves on the landscape trees are just budding out. Forsythia and Redbud are just starting. We average about 100 to 120 growing days between first and last frost. The farm, 9 miles east of South Haven Michigan had nearly identical cold this winter, and about 18 inches, or half a meter more snow than my home in Illinois, but otherwise it was very similar.
So I hate schlepping trees in and out of my preferred winter shelter, and have been experimenting with just leaving trees lay out for the winter. I do take trees off the benches, and set them on the ground. But that is about it. On the ground they do get some thermal buffering from the soil below, and I do group them a bit which gives some wind protection, but largely they all spend the winter pretty exposed. And they do get some sun in winter. I used to think winter sun was the ''boogeyman'', but I have found it is not as big a deal as I thought. I tend to do this only with trees in larger pots, usually gallon larger nursery pots and or Anderson flats. I have found that even ''good'' meaning ''expensive'' bonsai pottery that is advertised as freeze-thaw resistant is often not freeze-thaw resistant. So trees in ''good'' pots get protected in my well house for the winter.
So here are some trees that have done well this winter.
Pinus banksiana - Jack Pines, my 2 in Anderson flats look great, I have a number of seedlings in mesh walled 'Sorce Pots' (@sorce ) and in 4 inch plastic pots. Some of these were left on their benches all winter, the Anderson flats and the majority were set on the ground. All have greened up and new buds are growing this spring. No losses. Jack pines are definitely the most winter hardy pine I know of. 5th year of wintering without protection 100% hardy. In theory hardy through zone 3 - do try them if you are in the northern tier of states. They might not do well in zone 7 or warmer, but in zone 7 you can leave JBP outdoors all winter, so you don't need Jack pine.
Chamaecyparis obtusa - Hinoki - I used to winter these in the well house, thinking Japan is more like St Louis than Chicago. This is the 3rd year I've left Hinoki out on the ground in an Anderson flat, and no problems. I'd say 100% hardy, but do take it off the bench and set it on the ground for winter.
Pinus bungeana - Chinese Lacebark Pines - I have starting 4th year seedlings, some in an Anderson flat and some in individual 4 inch pots. All spent the winter on the ground and no losses, this is 2 winters in a row. First winter after seed sprouted I did move the flats into the well house. I believe this pine will prove winter hardy in containers throughout zone 5. (@Owen Reich )
Celastrus sp. I think C. orbiculatus - Oriental bittersweet - It could be C. scandens, I have not checked. In gallon containers and 4 inch pots, perfectly winter hardy.
Amelanchier x grandiflora - Service berry - have 2 that have never missed a beat, flower buds are just starting to show. This is an underrated member of the apple family, really nice early spring flowers before leaves fully expand. 100% winter hardy.
Tsuga canadensis - I have one in a 5 gallon nursery pot and a batch of 5 seedlings, about 5 years old in an Anderson flat. The Anderson flat stays on its bench, fully exposed all winter, the nursery pot is on the ground - 100% hardy, no sign of any distress.
Acer ginnala - Amur Maple - I have 2, one in a 5 inch pot, one in a 3 gallon pot. Both are more than 5 years old, never wintered anywhere but outside, on the ground. 100% winter hardy.
Malus hybrid - a crab apple, - don't remember which, one of the weeping crap varieties. I bud grafted onto apple understock some years ago when trying to learn grafting. Both pots on the ground, no protection, flower buds are starting to show. 100% hardy.
Pinus ponderosa - Ponderosa pine - I moved these to Michigan because the back yard was getting to shady. Wintered in full sun, just set on the ground. Looking fabulous, healthier than they every looked in my too shady back yard. These really need full sun to stay healthy, sun in winter is no problem.
Picea engelmannii and pungens - Engelmann spruce and Colorado blue spruce - All did well, full sun, just set on the ground. I have a weeping cultivar of engelmann spruce, and one weeper of Colorado blue spruce, also have grafted varieties of blue spruce, all do fine with no protection.
Picea glauca var densata and Picea orientalis and Picea omorika - all do well juet set on the ground and no extra protection.
Wisteria macrostachya - in a 4 inch diameter pot - just set on ground - did fine.
Chionanthus virginicus - American Fringe tree - has done well 2 winters in a row, both specimens are in 5 gallon and 20 gallon pots. - 3 winters and no problems.
Vaccinium corymbosum - blueberries - select cultivars of highbush blueberries - I have explants from tissue culture and various cuttings sizing up to get them big enough that ''the kid'' can see them from the driver seat of the tractor, so he don't mow them over. Will get planted in the field when about 1 gallon size. These all winter in flats, on the ground. No problems at all.
Carpinus caroliniana - Hornbeam - collected one from the farm, does fine in a cut down nursery pot, set on the ground.
Ostrya virginiana - Hop flowered hornbeam - perfectly hardy even in small 3 and 4 inch pots.
Lycium barbarum - goji berry - One gallon container - set on ground - perfectly hardy 2 winters in a row.
Junipers - virginiana, horizontalis - blue rug, shimpaku, itoigawa, & kiushu, - all in various containers, no winter problems at all. The blue rug, J horizontalis got left on top of the bench and had no problems. All perfectly winter hardy.
Metasequoia - Dawn Redwoods - these are outstandingly hardy. I have left them on the ground and on the bench, and all have survived no problems 3 winters. These are much hardier than bald cypress.
Elms - Ulmus pumila - Siberian elm - left outside, no problems, no protection fully exposed. I have not tested Seiju elm yet. It is supposed to be hardy enough.
Parthenocissus quinquefolia - Virginia creeper - this is another amazingly hardy vine, I leave it fully exposed, just set on the ground in winter.
Chaenomeles hybrids -Japanese Flowering quinces - I have the varieties 'Contorted White', 'Iwai Nishiki' and what I believe is 'Minerva' and these get left out all winter. Just set on the ground. they do fine. These are all larger leaf, larger tunks, more robust types. 'Chojubai', 'Kan Toyo' & 'Hime' need protection, these are small leaf types, and seem to be less hardy in a pot. They might be okay in the ground, but in a pot they need protection. So Chaenomeles, are a some can take it, some can not.
**********************************************************************
Failures - or trees I feel I must protect
Ginkgo - for what ever reason, ginkgo are hardy when planted in the ground as landscape trees, but as a tree in a pot I have had no success wintering them on the ground, or on the bench. I bring my ginkgos into the well house. NOT Reliably WINTER HARDY in 5b
Beech - Fagus - I bring these into the well house, have lost all that wintered unprotected. Even though winter hardy in landscape, they seem to be a problem in a pot.
Japanese Black Pine - Pinus thunbergii - in theory they look like they could be hardy in zone 5, in practice they are not. They might survive one or two winters, but usually within 5 years one winter or another will wipe them out. Also, given my micro-climate, JBP do not wake up on time in spring, because I have cool spring weather. They need heat to ''wake up'' - this means they get short changed on length of growing season. This means that many years my JBP can not be treated as 2 flush pines, they barely have time for one flush of growth. JBP are problematic. Especially since my only JBP experience is the cork bark varieties, I don't grow the normal type.
Satsuki azalea - I love them, love the flowers, they are not hardy here. They do well in cold dark storage for the winter, no unusual leaf drop or any reduction in blooming. Well house is mandatory for them. Zone 7, maybe 6b, no need to test them in zone 5.
Taxodium distichum - Bald Cypress - in the landscape these are perfectly hardy, but in pots are marginal. Had them survive some winters, and fail other winters. Have taken to wintering them in the well house. Must be protected in zone 5
Bamboo - Phyllostachys atrovaginata, aureosulcata, Pleioblastus viridistriatus, and Indocalamus latifolius - all 4 species are perfectly hardy when planted in the ground in the landscape - but planted in pots are not quite winter hardy. Must protect bamboo in winter if in pots. Also include Phyllostachys nigra, black bamboo - which is not winter hardy much north of zone 7.
Japanese Maples, - Acer palmatum - need protection. even though hardy in the landscape.
So that is my ''report''
I post this because I hear of many are going through great lengths to protect trees in winter that are species that are more than winter hardy enough. The great thing about leaving them lay out all winter is you never have to do the ''in and out'' dance with them. My back aches at the thought of running around moving trees just before dark to avoid the frost. I refuse to do it. I am just now beginning to empty my well house, most of my local buddies have been doing the dance with their trees for several weeks now.
So get brave, if you have any of the trees on the winter hardy list, don't baby them, just set them on the ground for the winter. It will save your back in the long run.