Introduction.

[Leo in N E Illinois]

At top of this page was some discussion on how to winter trees (page 8). My many years of experience does indeed back up the idea that it is best if the trees freeze once in autumn, stay frozen all winter, then thaw once in spring. Of course this is not really possible but greenhouse storage in the winter where the tree daily goes through a daily (or nightly) freeze and thaw when the sun comes out cycle is really brutal on the trees. Much better to site winter storage in an area that will get shade all winter. That way the number of freeze and thaw cycles will be minimized. Unheated greenhouses are terrible places to winter trees if they get sun. If you want to use a greenhouse to winter trees, cover the glass or glazing with opaque tarps or plywood or other light blocking material to keep the greenhouse at ambient air temperature or cooler.

I live in zone 5b, and have had surprising good success just setting pots on the ground, in the shade with minimal mulch. As long as the tree in the pot is hardy through zone 5, I have had good success just setting pots on the ground in zone 5b. Don't try this with zone 7 trees in zone 5. But do try it with zone 5a and zone 4 hardy trees in zone 5b.

Generally if a tree is sold for outdoor landscape use in your climate, you frequently can just winter the tree by setting the pot on the ground in a shady spot for the winter. The heat from the ground keeps the roots just a few degrees warmer than air temps. A little mulch to the pot rim will help also. Don't add mulch until after ground freezes or mice and voles will move in and munch on tree trunks over the winters. Bare ground until after voles and mice have set up their winter homes. (hopefully away from your trees). I also use a wire mesh lined dog crate on the ground, the wire mesh keeps squirrels and vermin out. Depending on your location, you should make sure your bonsai wintering set up keeps out, or does not attract voles, mice, ground squirrels or rabbits or other chewing varmints.

If wintered outdoors, in the shade, you will not have trouble with trees coming out of dormancy too early. Over 40 years of bonsai I have learned to hate the "in and out dance", where something breaks dormancy too early, and the only way to get tight growth is to put outside in the day, and protect from freezing back inside at night.

 

[Frozentreehugger]

At top of this page was some discussion on how to winter trees (page 8). My many years of experience does indeed back up the idea that it is best if the trees freeze once in autumn, stay frozen all winter, then thaw once in spring. Of course this is not really possible but greenhouse storage in the winter where the tree daily goes through a daily (or nightly) freeze and thaw when the sun comes out cycle is really brutal on the trees. Much better to site winter storage in an area that will get shade all winter. That way the number of freeze and thaw cycles will be minimized. Unheated greenhouses are terrible places to winter trees if they get sun. If you want to use a greenhouse to winter trees, cover the glass or glazing with opaque tarps or plywood or other light blocking material to keep the greenhouse at ambient air temperature or cooler.

I live in zone 5b, and have had surprising good success just setting pots on the ground, in the shade with minimal mulch. As long as the tree in the pot is hardy through zone 5, I have had good success just setting pots on the ground in zone 5b. Don't try this with zone 7 trees in zone 5. But do try it with zone 5a and zone 4 hardy trees in zone 5b.

Generally if a tree is sold for outdoor landscape use in your climate, you frequently can just winter the tree by setting the pot on the ground in a shady spot for the winter. The heat from the ground keeps the roots just a few degrees warmer than air temps. A little mulch to the pot rim will help also. Don't add mulch until after ground freezes or mice and voles will move in and munch on tree trunks over the winters. Bare ground until after voles and mice have set up their winter homes. (hopefully away from your trees). I also use a wire mesh lined dog crate on the ground, the wire mesh keeps squirrels and vermin out. Depending on your location, you should make sure your bonsai wintering set up keeps out, or does not attract voles, mice, ground squirrels or rabbits or other chewing varmints.

If wintered outdoors, in the shade, you will not have trouble with trees coming out of dormancy too early. Over 40 years of bonsai I have learned to hate the "in and out dance", where something breaks dormancy too early, and the only way to get tight growth is to put outside in the day, and protect from freezing back inside at night.

As I said Leo everyone should use what works for them . My personal experience lead to my winterization technique. I lost trees native zone 4 trees outside . I don’t have your experience .but dead trees make you gun shy . I do what I do because it works for me . Never lost a tree in the shed including zone 5 conifers . Of course there can be other variables . Weather and zones are fascinating subject . I love zone 4 south of Ottawa admit there is a zone change to 5 not that far south of me . My understanding is it’s the effect of the Great Lakes moderation of the weather . Even at my place same zone as Ottawa . It is almost always 1 to 2 degrees C warmer in winter and cooler in summer . The shed gives me piece of mind not sure what I fear more . Those mid January thaws then deep freeze the next day or the wind . I live in a town . But the farm land around me is flat for like 40 miles around me . I agree 100 percent what you said about green house . Got to be hard as hell on trees . I may retry outside with some trees in training but like I said gun shy . Why mess with success

 

[19Mateo83]

@Cajunrider bro you talked me into it got me a BC cultivar is Shawnee brave . Not destined to be a bonsai and technically not mine ( wait a minute I paid for it ) went Canada day long weekend sale shopping at the nursery was the wife’s choice as new front yard tree Hope it works out we are borderline it’s cold range

I’d be multiplying the front yard tree as soon as those branches are thick enough to air layer. Then you can have lots and lots of BC and the wife can have her landscape tree

 

[Frozentreehugger]

I’d be multiplying the front yard tree as soon as those branches are thick enough to air layer. Then you can have lots and lots of BC and the wife can have her landscape tree

bro I assume your married so you will understand . There is a verbal agreement that it is her tree . Therefore I need her permission to cut pieces off it . With that look as we were driving home with it . but the small nursery has 2 others . Days there not popular but he keeps a couple in stock . My biggest problem is I have lots of space but limited full sun . If I did not like sun loving trees be no problem

 

[Leo in N E Illinois]

As I said Leo everyone should use what works for them . My personal experience lead to my winterization technique. I lost trees native zone 4 trees outside . I don’t have your experience .but dead trees make you gun shy . I do what I do because it works for me . Never lost a tree in the shed including zone 5 conifers . Of course there can be other variables . Weather and zones are fascinating subject . I love zone 4 south of Ottawa admit there is a zone change to 5 not that far south of me . My understanding is it’s the effect of the Great Lakes moderation of the weather . Even at my place same zone as Ottawa . It is almost always 1 to 2 degrees C warmer in winter and cooler in summer . The shed gives me piece of mind not sure what I fear more . Those mid January thaws then deep freeze the next day or the wind . I live in a town . But the farm land around me is flat for like 40 miles around me . I agree 100 percent what you said about green house . Got to be hard as hell on trees . I may retry outside with some trees in training but like I said gun shy . Why mess with success

There's definitely more than one way to winter trees. I have a well house where my zone 6 and zone 7 trees are wintered. It is the equivalent of a shed that never gets below freezing. Half my trees go there.

 

[Cajunrider]

There's definitely more than one way to winter trees. I have a well house where my zone 6 and zone 7 trees are wintered. It is the equivalent of a shed that never gets below freezing. Half my trees go there.

Well. This fall I will have to go up to PA and figure out how to winter my trees up there.

 

[ShadyStump]

I'm already brainstorming my winter set up this year. Not the best luck this past winter, but that was partly due to a couple trees in water retentive soil that was great for a hot, dry summer, but rotted the roots as soon as things cooled down.
I'm in one of those climates where freeze/thaw cycles are nightly occurrences much of the winter, so outdoor wintering is tricky for most species. February is monster around here, though. January get the coldest average, but February is where we get <0F snaps on top of the normal daytime thaws.


Considering getting a couple giant storage tubs and digging them into ground.
But first benches for the rest of the year. Picked up some jute rope and going to try my boyscout skills on some polls I pulled out of my dad's burn pile. Failing that, I'll use whatever scrap lumber I can scrounge. That stuff is too expensive to pay for now days.

 

[Frozentreehugger]

There's definitely more than one way to winter trees. I have a well house where my zone 6 and zone 7 trees are wintered. It is the equivalent of a shed that never gets below freezing. Half my trees go there.

What’s your thoughts @Leo in N E Illinois my winter facility as said before un heated insulated building no light . What if I added heat to keep it above freezing then I could also keep less hardy trees but my concern is . Will I need light . My belief has always been froze dormant no light needed like a tree under snow . But if it’s above freezing do I need light

 

[Cajunrider]

I'm already brainstorming my winter set up this year. Not the best luck this past winter, but that was partly due to a couple trees in water retentive soil that was great for a hot, dry summer, but rotted the roots as soon as things cooled down.
I'm in one of those climates where freeze/thaw cycles are nightly occurrences much of the winter, so outdoor wintering is tricky for most species. February is monster around here, though. January get the coldest average, but February is where we get <0F snaps on top of the normal daytime thaws.


Considering getting a couple giant storage tubs and digging them into ground.
But first benches for the rest of the year. Picked up some jute rope and going to try my boyscout skills on some polls I pulled out of my dad's burn pile. Failing that, I'll use whatever scrap lumber I can scrounge. That stuff is too expensive to pay for now days.

You can do it!

 

[Frozentreehugger]

I'm already brainstorming my winter set up this year. Not the best luck this past winter, but that was partly due to a couple trees in water retentive soil that was great for a hot, dry summer, but rotted the roots as soon as things cooled down.
I'm in one of those climates where freeze/thaw cycles are nightly occurrences much of the winter, so outdoor wintering is tricky for most species. February is monster around here, though. January get the coldest average, but February is where we get <0F snaps on top of the normal daytime thaws.


Considering getting a couple giant storage tubs and digging them into ground.
But first benches for the rest of the year. Picked up some jute rope and going to try my boyscout skills on some polls I pulled out of my dad's burn pile. Failing that, I'll use whatever scrap lumber I can scrounge. That stuff is too expensive to pay for now days.

There is heat of course in the ground . For example I know a guy that built a greenhouse . First he dug a hole 4 feet deep so it’s bellow the frost line then he insulated the walls of the hole with styrofoam. Insulation bottom is open . Then he backfilled the hole with chrushed stone . The green house is above this . A surprising amount of heat transfers up thru the stone in winter

 

[Cajunrider]

There is heat of course in the ground . For example I know a guy that built a greenhouse . First he dug a hole 4 feet deep so it’s bellow the frost line then he insulated the walls of the hole with styrofoam. Insulation bottom is open . Then he backfilled the hole with chrushed stone . The green house is above this . A surprising amount of heat transfers up thru the stone in winter

If I own a house up north I would definitely try a low temp geothermal green house.

 

[Frozentreehugger]

If I own a house up north I would definitely try a low temp geothermal green house.

Depends what you mean by fro thermo . When are you planning to move to PA

 

[Leo in N E Illinois]

What’s your thoughts @Leo in N E Illinois my winter facility as said before un heated insulated building no light . What if I added heat to keep it above freezing then I could also keep less hardy trees but my concern is . Will I need light . My belief has always been froze dormant no light needed like a tree under snow . But if it’s above freezing do I need light

Ah, the eternal conundrum. Its tricky. The beauty of well houses is they are below ground, and temperature variation is minimal. Here's the scoop.

KEY: IF you can keep your temperature between 0 C and 4 C, also known as 32 F to 40 F, NO LIGHT NEEDED. At tese temperatures metabolism is so slow that both deciduous and most conifers functionally do not need light. they can coast along on stored sugars for a 4 to 5 month dormancy. However just a week or so of temps over 40 F (4 C) and dormant trees can start growing. In the dark this means etiolated (colorless, elongated & weak) growth. So if you can keep your shed below 40 F, it can be totally dark.

Usually in autumn, when trees are put into storage, a few days, even weeks above 40 F won't cause much growth. But in late January or February or March, when too early to come out for spring growth, a few warm days can start trees growing on you. I actually gave up growing Japanese maples, because they break dormancy very quickly. In my yard it is not safe to put them outside until May, and usually JM in my well house end up breaking dormancy in March or April meaning months of the "in and out dance", or if I can find a windowsill or spot under lights, the foliage grown indoors is always weak and elongated compared to outdoor grown foliage. Then there's getting the maple outside, and having to remove all the foliage that grow indoors with a late spring pruning, so that the new foliage is all outdoor grown tight foliage. JM are a pain in the arse in cold climates.

But most trees stay nice and dormant as long as it is less than 40 F, they stay dormant and NO LIGHT IS NEEDED.

Above 40 F, here we get some metabolism going fast enough that light is needed. As long as the temperatures are below 50 F, the light needed to keep good color, slow growth and compact growth will not need to be as bright as full sun outdoors, but this will be species dependent. Azalea, sub-tropicals that are normally evergreen will grow slow enough that fluorescent light will be bright enough to get relatively normal growth. Trees from northern climates that normally grow fast in cool weather, like Larix, Larch will absolutely need the equivalent of full sun if they break dormancy while in storage. Larch grow rapidly at cool 40 F temperatures. If your larch breaks dormancy, you are doomed to the "in and out dance". There is a larch grower in Minnesota that installed an air conditioner with a modified thermostat to keep his storage shed below 38 F in late winter until it was safe to bring his larches out in spring. He has too many to do the "in and out dance", so refrigerates his storage rather than deal with early breaking of dormancy.

So if your temperatures are above 40 F you need to add light for evergreen tree. For deciduous trees, keep an eye on them, at temps above 40 F there is a good chance they will begin growing once their "chill requirement" has been met. Maples can start growing 2 months before last frost. This makes for a difficult situation. As few as 5 days above 40 F will trigger a maple into growing. (which is why I don't have JM) Elms, azalea and others need longer "warm spells" to break dormancy, but 2 weeks above 40 F will get MOST trees to begin to break dormancy, meaning most trees will need light once temps are above 40 F.

A greenhouse to winter trees is one option, heat the greenhouse to keep it at or above freezing, because freeze thaw cycling is rough on trees. Have automatic vents to prevent temps on warm late winter days from climbing over 70 F. By keeping above freezing, when trees break dormancy they can get enough light to grow normally, until safe enough to put outdoors.

So the theme is below 40 F - no light needed. Above 40 F - light is needed. Below 40 F metabolism is slow enough stored sugar is adequate to keep the tree alive. Above 40 (4 C ) metabolism does consume enough sugars that tree is no longer fully dormant.

Below 40F (4 C) dormancy requirement is easily satisfied for most deciduous species and most evergreen species and coniferous species can be held dormant at temperatures below 40 F. Most zone 7 to zone 5 species need 12 weeks of dormancy. Zone 4 to 3 species often need longer, usually 16 weeks will satisfy the dormancy requirements. There are species specific exceptions.

Above 40 F (4 C) it is hit or miss as to what will stay dormant, every degree above 40 F more species of tree become active, requiring light. Some will need equivalent of full sun (Larch and alpine trees) some can limp along on lower light levels at cooler temperatures. For example below 50 F azalea will be fine with fairly dull fluorescent illumination. What will survive in low light and cool temps and what will need "full sun" once they start growing is species specific.

 

[Frozentreehugger]

Ah, the eternal conundrum. Its tricky. The beauty of well houses is they are below ground, and temperature variation is minimal. Here's the scoop.

KEY: IF you can keep your temperature between 0 C and 4 C, also known as 32 F to 40 F, NO LIGHT NEEDED. At tese temperatures metabolism is so slow that both deciduous and most conifers functionally do not need light. they can coast along on stored sugars for a 4 to 5 month dormancy. However just a week or so of temps over 40 F (4 C) and dormant trees can start growing. In the dark this means etiolated (colorless, elongated & weak) growth. So if you can keep your shed below 40 F, it can be totally dark.

Usually in autumn, when trees are put into storage, a few days, even weeks above 40 F won't cause much growth. But in late January or February or March, when too early to come out for spring growth, a few warm days can start trees growing on you. I actually gave up growing Japanese maples, because they break dormancy very quickly. In my yard it is not safe to put them outside until May, and usually JM in my well house end up breaking dormancy in March or April meaning months of the "in and out dance", or if I can find a windowsill or spot under lights, the foliage grown indoors is always weak and elongated compared to outdoor grown foliage. Then there's getting the maple outside, and having to remove all the foliage that grow indoors with a late spring pruning, so that the new foliage is all outdoor grown tight foliage. JM are a pain in the arse in cold climates.

But most trees stay nice and dormant as long as it is less than 40 F, they stay dormant and NO LIGHT IS NEEDED.

Above 40 F, here we get some metabolism going fast enough that light is needed. As long as the temperatures are below 50 F, the light needed to keep good color, slow growth and compact growth will not need to be as bright as full sun outdoors, but this will be species dependent. Azalea, sub-tropicals that are normally evergreen will grow slow enough that fluorescent light will be bright enough to get relatively normal growth. Trees from northern climates that normally grow fast in cool weather, like Larix, Larch will absolutely need the equivalent of full sun if they break dormancy while in storage. Larch grow rapidly at cool 40 F temperatures. If your larch breaks dormancy, you are doomed to the "in and out dance". There is a larch grower in Minnesota that installed an air conditioner with a modified thermostat to keep his storage shed below 38 F in late winter until it was safe to bring his larches out in spring. He has too many to do the "in and out dance", so refrigerates his storage rather than deal with early breaking of dormancy.

So if your temperatures are above 40 F you need to add light for evergreen tree. For deciduous trees, keep an eye on them, at temps above 40 F there is a good chance they will begin growing once their "chill requirement" has been met. Maples can start growing 2 months before last frost. This makes for a difficult situation. As few as 5 days above 40 F will trigger a maple into growing. (which is why I don't have JM) Elms, azalea and others need longer "warm spells" to break dormancy, but 2 weeks above 40 F will get MOST trees to begin to break dormancy, meaning most trees will need light once temps are above 40 F.

A greenhouse to winter trees is one option, heat the greenhouse to keep it at or above freezing, because freeze thaw cycling is rough on trees. Have automatic vents to prevent temps on warm late winter days from climbing over 70 F. By keeping above freezing, when trees break dormancy they can get enough light to grow normally, until safe enough to put outdoors.

So the theme is below 40 F - no light needed. Above 40 F - light is needed. Below 40 F metabolism is slow enough stored sugar is adequate to keep the tree alive. Above 40 (4 C ) metabolism does consume enough sugars that tree is no longer fully dormant.

Below 40F (4 C) dormancy requirement is easily satisfied for most deciduous species and most evergreen species and coniferous species can be held dormant at temperatures below 40 F. Most zone 7 to zone 5 species need 12 weeks of dormancy. Zone 4 to 3 species often need longer, usually 16 weeks will satisfy the dormancy requirements. There are species specific exceptions.

Above 40 F (4 C) it is hit or miss as to what will stay dormant, every degree above 40 F more species of tree become active, requiring light. Some will need equivalent of full sun (Larch and alpine trees) some can limp along on lower light levels at cooler temperatures. For example below 50 F azalea will be fine with fairly dull fluorescent illumination. What will survive in low light and cool temps and what will need "full sun" once they start growing is species specific.

Thanks Leo as always your experience is greatly appreciated. Basically explains why I struggled . With trees outside and the shed frozen no light or wind is effective . Not to mention my brief fling with JM years ago that was a disaster . Like I said I try my best to keep them froze until they can thaw safely . End result is the conifers lose a slight amount of colour in no light and the decid are behind the progress of outdoor trees but all respond like gang busters to the light . I go full sun in the spring . That next step for less hardy trees will be a bitch not sure I have the effort in me at my age thanks for the info on larch I don’t have any . Can’t find a killer collected tree to picky I guess . Problem is yo here there is some amazing larch bonsai to compare average won’t do

 

[Frozentreehugger]

Interesting native tree . Killing time walk thru the Canadian National arboretum first 2 pics are fern leaf beech leaves are maybe 25 to 30 percent the size of beech leaves . The mulberry I have never seen a bonsai of but looks great with dead wood and medium size weeping leaves tree in pic is about 3.5 feet high

 

[HorseloverFat]

Interesting native tree . Killing time walk thru the Canadian National arboretum first 2 pics are fern leaf beech leaves are maybe 25 to 30 percent the size of beech leaves . The mulberry I have never seen a bonsai of but looks great with dead wood and medium size weeping leaves tree in pic is about 3.5 feet high

SOOO COOL!

 

[HorseloverFat]

Ok folks!!!

I'm planning a "Mid-Winter Virtual Check-In"

Using the discord server set up by the incomparable @Paradox ...

I am THINKING the evening of Jan 28th...

But what are YOU guys thinkin'?

 

[HorseloverFat]

 

[19Mateo83]

Welcome back brotha! Everything is looking great and happy to see you and the boys thriving!

 

[HorseloverFat]

Welcome back brotha! Everything is looking great and happy to see you and the boys thriving!

Thank you so much, breddah!!!

I have to "get back at" them punica repots... But I will be assessing all of my notifications/PMs, soon!!