snow insulation

[Deep Sea Diver]

This is a great discussion folks!

I'm finding there are plenty of nuances that might be better considered when protecting bonsai trees during the winter. Type of tree/cultivar, Sun and WInd exposure, freezing and thawing rate, watering/desiccation and drainage, rate of freezing and unfreezing of the root ball and maybe more. (Then there's damage control for situations like bark splitting and sun scald.)

I've been considering the data I'm measuring from the different locations over time, green house, cold frame, under shelter, exposed, and on the shelf and the implications while diving into the research. First thing I found is the researchers started studying the above ground effects of freezing/cold tolerance.... as studying what happens to the roots only recently. It was too hard as one of the latest review studies mentioned.

The question I first started investigating, how do different forms of protection in different storage locations protect a bonsai tree's roots (stem/branches/buds are a whole another thing) has spawned further questions which I won't bore folks with at the moment.

I'm hoping for another good freeze (sorry Puget Sound folks!) for more data. This present week's data is helping clarify some of the picture. But muddying the waters on other fronts. I will put forward the following, perhaps provoking, statements as food for thought.

• All species of trees are not created equal in regards to cold hardiness.
• The same tree can have a difference in cold hardiness one winter versus the next... or even in the same winter.... depending upon the weather during paradormancy and the first stage of endodormancy.... and the later on, the weather during endodormancy and ectodormancy.
• Tree roots are not evolved to handle the freezing temperatures and other extremes that trunks/branches/buds were.
• Root damage can be subtle and hard to notice as budding is independent of root growth.... and even microdamage to the growing tips of the roots, where it will start first, will be at the expense of the next year's overall growth making it very hard to acknowledge by a hobbyist.
• A frozen root ball is not the best thing for a tree, especially for extended periods of time. Some trees stems can handle the subsequent loss of water supply from the roots better then others. Especially if stored using layers of protection (see above factors) yet that doesn't mean subtle damage to the trunk, branches and buds isn't occurring over time.
• Measuring the soil temperature under a bonsai pot is not an accurate indication of what is occurring within the media in the pot. The data I gathered showed the media inside a pot with a bonsai tree planted inside placed upon the ground was frozen (put in place 3 weeks before the freeze) while the soil temperature right beside these pots remained 2-3F warmer in each of the three key locations. (cold frame, under shelter, no shelter).... This particular data was taken during a 10 day period Dec/Jan last.
• Putting most trees on the ground is a good first step. Burying them in the ground is better. Cold frame is even better. The data shows none of these locations will protect the bonsai in a pot's root ball from freezing. Even when mulched and covered with snow. None.
• The more "layers of protection" as mentioned above, the more moderation the tree experiences in its journey into, during and when leaving a freeze.

Gosh, so sorry to go on and on. That's all folks!

Cheers
DSD sends

 

[rockm]

For everyone that leaves there trees on the ground all year (mulched or unmulched) do you have any problem with critters? Curious. I am in Atlanta so I leave mine on my benches unless it drops below 25 or so. Then I move to the ground or garage. Only exception is I have a cork oak I add more care too. I have mulched on the bench too. I would definitely be slightly more cautious if I had a high dollar tree. I am building a new setup and would like to have space to set them on the ground every year and mulch in but have been worried about animals.

Haven't had a problem with critters for 25 years, but I have fenced backyard that deer won't go over. Rabbits, squirrels, chipmunks are all over the place. The wet mulch piles aren't attractive as shelter. If I put a cover over the mulch piles, I would probably have a problem. I have more issues with chipmunks and squirrels while the trees are on the benches in the spring and summer.

 

[Ohmy222]

Haven't had a problem with critters for 25 years, but I have fenced backyard that deer won't go over. Rabbits, squirrels, chipmunks are all over the place. The wet mulch piles aren't attractive as shelter. If I put a cover over the mulch piles, I would probably have a problem. I have more issues with chipmunks and squirrels while the trees are on the benches in the spring and summer.

thanks, makes sense. I have read of issues with burying trees and cold frames but I wouldn't really have a cover on them. More like a nice area to put them on the ground and mulch them in.

 

[kale]

Here’s my collection hibernating in a window well. Stays between 30f-40f constantly!

 

[penumbra]

Here’s my collection hibernating in a window well. Stays between 30f-40f constantly!View attachment 417463

Do you cover your window well or is it open on top? Do you ever crack the window slightly open?

 

[PA_Penjing]

Actually, while I like a little snow on my trees, I don't want the tree fully covered as snow has a tendency to tear branches off nicely refined bonsai as it slowly melts/refreezes and turns to ice over time.

Surprised I don't hear this complaint more often. In the past I have attempted to leave trees out in the snow and had large parts of trees torn off by melting and thawing snow. On a sunny day the snow will melt and get slushy then freeze solid at night. It makes this kind of heavy snow/ice lasagna that can do serious damage as it pulls branches down in slow motion for a few weeks. But I guess that's a problem not everyone has. It's very typical where I live to have nights in the twenties and day time temps above freezing. Not this year (thankfully) but a precaution for anyone who lives somewhere cold but not that cold

 

[penumbra]

Do you ever crack the window slightly open?

I should have looked closer. It seems that you do open the window slightly.

 

[Shogun610]

I

This is a great discussion folks!

I'm finding there are plenty of nuances that might be better considered when protecting bonsai trees during the winter. Type of tree/cultivar, Sun and WInd exposure, freezing and thawing rate, watering/desiccation and drainage, rate of freezing and unfreezing of the root ball and maybe more. (Then there's damage control for situations like bark splitting and sun scald.)

I've been considering the data I'm measuring from the different locations over time, green house, cold frame, under shelter, exposed, and on the shelf and the implications while diving into the research. First thing I found is the researchers started studying the above ground effects of freezing/cold tolerance.... as studying what happens to the roots only recently. It was too hard as one of the latest review studies mentioned.

The question I first started investigating, how do different forms of protection in different storage locations protect a bonsai tree's roots (stem/branches/buds are a whole another thing) has spawned further questions which I won't bore folks with at the moment.

I'm hoping for another good freeze (sorry Puget Sound folks!) for more data. This present week's data is helping clarify some of the picture. But muddying the waters on other fronts. I will put forward the following, perhaps provoking, statements as food for thought.

• All species of trees are not created equal in regards to cold hardiness.
• The same tree can have a difference in cold hardiness one winter versus the next... or even in the same winter.... depending upon the weather during paradormancy and the first stage of endodormancy.... and the later on, the weather during endodormancy and ectodormancy.
• Tree roots are not evolved to handle the freezing temperatures and other extremes that trunks/branches/buds were.
• Root damage can be subtle and hard to notice as budding is independent of root growth.... and even microdamage to the growing tips of the roots, where it will start first, will be at the expense of the next year's overall growth making it very hard to acknowledge by a hobbyist.
• A frozen root ball is not the best thing for a tree, especially for extended periods of time. Some trees stems can handle the subsequent loss of water supply from the roots better then others. Especially if stored using layers of protection (see above factors) yet that doesn't mean subtle damage to the trunk, branches and buds isn't occurring over time.
• Measuring the soil temperature under a bonsai pot is not an accurate indication of what is occurring within the media in the pot. The data I gathered showed the media inside a pot with a bonsai tree planted inside placed upon the ground was frozen (put in place 3 weeks before the freeze) while the soil temperature right beside these pots remained 2-3F warmer in each of the three key locations. (cold frame, under shelter, no shelter).... This particular data was taken during a 10 day period Dec/Jan last.
• Putting most trees on the ground is a good first step. Burying them in the ground is better. Cold frame is even better. The data shows none of these locations will protect the bonsai in a pot's root ball from freezing. Even when mulched and covered with snow. None.
• The more "layers of protection" as mentioned above, the more moderation the tree experiences in its journey into, during and when leaving a freeze.

Gosh, so sorry to go on and on. That's all folks!

Cheers
DSD sends

Interesting so even if soil is frozen at 32F with a layer of snow and leaves causes damage? What about root death at temperatures below that, most root death damage occurred at temps lower around 15F for temperate trees.

there is a detailed table of temperate or commonly used Bonsai root death zones compared to top hardiness zone in Bonsai heresy , so if root ball temps are frozen and around 32f when insulated with snow , gets water when snow melts and stays above their minimal temperatures how would that cause damage?

I buried some trees in the ground last year that died because once the snow thawed or some melt since ground temperatures is warmer it cause water to sit and not percolate into ground because water table in my back yard is high so I went with placing stuff on ground w layer of leaves next to home that now has snow but no snow on any branches

 

[Dav4]

I buried some trees in the ground last year that died because once the snow thawed or some melt since ground temperatures is warmer it cause water to sit and not percolate into ground because water table in my back yard is high so I went with placing stuff on ground w layer of leaves next to home that now has snow but no snow on any branches

This is why I've never considered burying potted trees.

 

[rockm]

This is why I've never considered burying potted trees.

Yep, burying them in the ground in their pots is a very bad idea. The pot won't drain and you have basically created a frozen swamp.

 

[Shogun610]

This is why I've never considered burying potted trees.

Yeah I’m glad I avoided that this year.

 

[Deep Sea Diver]

Respectfully do not agree about burying the pots in the ground comments above. Data show this is the safest place, given a properly prepared site.

Yet if one’s yard is just at the water table why would you even think of burying pots in the ground. Installing a cold frame on a base designed to drain is an easily available option.

As always in bonsai, the answer is, it depends. When burying the pot in the ground one must properly prepare the soil and the setting.

Burying pots in non draining soil is asking for death by slow suffocation in a muddy grave. Common sense would say that assuring proper drainage in bonsai is job one... to improve the drainage we bury our pots, at least 40 each year, in friable, draining soil with with medium bark nuggets under, around and over the pot. We use about six bags of bark nuggets a year for storage. Each year the soil get better.

In the past five years I’ve not had one loss to root rot. A rabbit did get inquisitive last year and chomped some of the small pre bonsai. Actually improved their look! This year theres a lightweight mist net around that location.

cheers
DSD sends

 

[Shogun610]

Respectfully do not agree about burying the pots in the ground comments above. Data show this is the safest place, given a properly prepared site.

As always in bonsai, the answer is always, it depends. When burying the pot in the ground one must properly prepare the soil and the setting.

Burying pots in non draining soil is asking for death by slow suffocation in a muddy grave. Common sense would say that assuring proper drainage in bonsai is job one... to improve the drainage we bury our pots, at least 40 each year, in friable, draining soil with with medium bark nuggets under, around and over the pot. We use about six bags of bark nuggets a year for storage. Each year the soil get better.

In the past five years I’ve not had one loss to root rot. A rabbit did get inquisitive last year and chomped some of the small pre bonsai. Actually improved their look! This year theres a lightweight mist net around that location.

cheers
DSD sends

I agree with the blanket “it depends” but you can’t bury your pots in the ground if you’re in a backyard like me , where the water table is very high. I’m close to a creek..with clay loam .. No matter what kind of preparation I did last year, whenever it rained or snow melted , the water table would be saturated to the point that everything had a puddle of water in the ground. So that’s why I went with other methods this year. For others it might work sure but for me it won’t.

 

[Deep Sea Diver]

That’s completely understandable. Each winter over location has its own quirks.

The concept of using “Layers of Protection” applies to all situations though…. using as many possible layers of protection to shield one’s bonsai, considering the geographic location, micro climate and composition of the bonsai collection applies. Bonsai hobbyists are by nature innovators so I’m sure you do so.

My collection is located in multiple areas, greenhouse, cold frame, under shelter and in the open depending on the species, condition and age of the plants. Each location uses multiple layers of protection.

For example one area uses windbreak on the prevailing wind and other directions, overhead protection, good drainage, digging the pots with medium bark nuggets surrounding the pots. The bark nuggets retain moisture, provide some insulation ensure drainage and can be pushed aside when temperatures rise to avoid fungus… and pushed back when temps dive.

Very similar practices many hobbyists use to protect their investments in time and manner..

Cheers
DSD sends

 

[kale]

I should have looked closer. It seems that you do open the window slightly.

@penumbra actually in the photo that is merely the screen resting on the window. I leave it closed at all times and not pictured at the top it has a cover that I have propped open about 6 inches. Does a good job trapping heat while still allowing for air flow.

 

[penumbra]

@penumbra actually in the photo that is merely the screen resting on the window. I leave it closed at all times and not pictured at the top it has a cover that I have propped open about 6 inches. Does a good job trapping heat while still allowing for air flow.

Perfect.

 

[Gary McCarthy]

Little bit of an update.

Temps have stayed frigid. Temps still in the single digits at night. The recorded temps of the sensor under the 2 feet of snow have started to dip a little to 28F. Temps here are supposed to warm up over the next few days. Curious to see if the temps under the snow will go back up to 32F, or if the ground temp will now keep it at 28F.

 

[Dav4]

Little bit of an update.

Temps have stayed frigid. Temps still in the single digits at night. The recorded temps of the sensor under the 2 feet of snow have started to dip a little to 28F. Temps here are supposed to warm up over the next few days. Curious to see if the temps under the snow will go back up to 32F, or if the ground temp will now keep it at 28F.

Aren't you due to get another snow dump this week? The Detroit area is expecting 12-18" Wednesday thru Thursday.

 

[Gary McCarthy]

Aren't you due to get another snow dump this week? The Detroit area is expecting 12-18" Wednesday thru Thursday.

Well............I'm hoping it all gets dumped in Detroit before it gets to me

We're supposed to warm up into the 40s and then cool off again with some snow in the forecast, but I don't think another 12" to 18". Plus I'm a little east and north of Buffalo. When the weather comes off Lake Erie it hits Buffalo, goes a little south of where I'm at, and then comes back up a little north and hits Rochester. Now, if the weather comes off Lake Ontario, then we get hammered.

 

[penumbra]

Well............I'm hoping it all gets dumped in Detroit before it gets to me

Don't we all