Damaging Temps?

[jimlau]

For the last 2 years I have been keeping my shohin size trees in a window well off my unheated garage. It is about 3’ deep and covered with a clear plastic molded cover that lets in light but is not airtight by any means. Last night we got down to 19.7 degrees F here in my backyard but in the window well it only dipped down to 36 degrees. Even though they are 3’ below ground level I can access them through a sliding window to check on them about once a week and give a little water as needed. And there is still enough air exchange so I don’t get any fungal buidlup. So don’t overlook unheated “natural” greenhouses like this for over wintering your small trees.

I guess putting shohin in a secured sealed bag in the fridge or freezer is no good? Freezer too cold, fridge with root rot or mold? If I put the tree outside and re-bag after temps go low would still not work?

 

[Paradox]

For the last 2 years I have been keeping my shohin size trees in a window well off my unheated garage. It is about 3’ deep and covered with a clear plastic molded cover that lets in light but is not airtight by any means. Last night we got down to 19.7 degrees F here in my backyard but in the window well it only dipped down to 36 degrees. Even though they are 3’ below ground level I can access them through a sliding window to check on them about once a week and give a little water as needed. And there is still enough air exchange so I don’t get any fungal buidlup. So don’t overlook unheated “natural” greenhouses like this for over wintering your small trees.

I put my satsuki and any other of my more sensitive plants in my window wells too, for the very reason that its a tad warmer in there

 

[Paradox]

I guess putting shohin in a secured sealed bag in the fridge or freezer is no good? Freezer too cold, fridge with root rot or mold? If I put the tree outside and re-bag after temps go low would still not work?

Fridge is generally not a great idea.
If not in a bag, it would dry out. In the bag would probably be too humid.
Besides the fact the space is very limited. You going to buy a fridge just for your trees and you only going to have just a few of them?
Outside, along the side of the house, protected by wind is always best

 

[rockm]

I have some black netting used to partially block the sun in the summer. Is it best to cover my trees with that netting, or could that maybe make upper branches get more pressure from accumulated snow?

Also would it attract too much heat, as it is black.

Thanks.

I wouldn't use it to cover trees, particularly not over them. That's asking for trouble with snow load and other things.

You don't really need to protect the TOPS of trees in winter, mostly only their roots. Snow load can be an issue, but unless its a heavy snowfall (like over 6 inches) not really much to worry about. Even then it's not an issue for most trees. Trying to remove that snow load will likely do more damage than the snow. Conifers can get quite loaded down with snow. I go out during heavy snows as its falling and shake limbs a bit to get the worst off.

I don't bother with deciduous trees. The pic below is of a two foot snowfall on my stored cedar elm and bald cypress.

 

[rockm]

I guess putting shohin in a secured sealed bag in the fridge or freezer is no good? Freezer too cold, fridge with root rot or mold? If I put the tree outside and re-bag after temps go low would still not work?

The Refrigerator is a very very bad place to store trees. The air inside the fridge is meant to be kept extremely dry and fridges are very good at doing that. They can desiccate trunks, branching and even roots. Sealing a tree in a plastic bag will likely cause mold mildew and other possibly more stressful things.

Inside is a VERY hostile environment for trees (tropical species included, although they only tolerate it better than temperate zone species)--low humidity--extremely low--well below the relative humidity of most deserts if you have the heat on. Very little air circulation. low light, are a few of the biggest issues.

If your trees are temperate zone species they should be outside under mulch or in an unheated structure. If you have been keeping them inside all summer, then you will have to keep them going indoors until spring, as they haven't acclimated themselves to handle cold. If they're elms, maples, pines, they're perfectly capable of withstanding winters outdoors if given the time to get ready. That readiness period begins in June and ends with the first freeze. Inside they miss the cues to begin preparing for winter.

 

[Ininaatigoons]

In the super cold places... Pick trees 2 zones colder than your location. Or trees that you can bring in such as Mediterranean. Because I haven't followed my own advice and put Acer Palmatum in the garage. I use a heater on super low setting when the Temps are going to go below 15 in the garage. This doesn't happen until until about -15 outside. I leave the Tamarack and Picea outside. This year I'm going to leave the silver maples and seedling reds out too.
Of course now that I'm deep into zone 5 I may throw the Palmatums in the ground

 

[Deep Sea Diver]

Gosh, there are always so many opinions on the granular level about protecting bonsai in winter weather. Just about everyone of these granular opinions are area specific and totally correct for their area. But as on can see each area has its own nuances.

1. Mulch trees in.
2. Protect from sun & wind
3. Ensure proper drainage
4. Water just before and after cold snaps
5. protect from rodents (there’s frequently a litany from folks on BN in spring who forgot this part.
Recommended locations include in garden beds next to home, window wells…( @kale brought this forwards years ago), under small tree large shrubs etc….

Given you have shohin here’s a quick, relatively cheap cold frame project idea for shohin. See image below of two example frames.



Materials: 8 PVC corners, PVC to match of length(s) needed, PVC glue, stakes, a hack saw, and a type of covering (shown is a type of greenhouse vinyl). Metal window screen optional.

a. Cut to desired size.
b. Glue together
c. Install covering, zip tie or other fastening. Ensure one side or, better still, the top. Ensure either opening can be easily opened to vent and be secured.
d. Stake down securely out of sun, wind.
e. Put in shohins, assuring proper drainage, mulch in.

For extra varmint protection: metal window screen can be fashioned around or inside and under cold frame, use aluminum wire for joins.

Close when temperatures are below 42 F.

Cheers
DSD sends

 

[dbonsaiw]

Same situation here. We have already had nights down to 27F one night and high 30s and low 40s the next.

Same. I've also been meaning to mulch over everything, but everything was frozen in the mornings. May need to be a nighttime project.

 

[shohin_branches]

So jealous of people where the pots freeze and stay frozen for most of winter. Here all winter is rollercoaster. We have JUST had our first sprinkle of snow. Temps to drop to ~ 22F at night till next week. Daytime around freezing. And next week 40-50F again. Typical winter weather, with a few random spots where nights can spike into the 0 F range.

You don't want your roots frozen long term, that's how branches dry out and die back. Being completely frozen also doesn't really count towards dormancy days. It's better to be cold than frozen, but then you have to water more often.

For the last 2 years I have been keeping my shohin size trees in a window well off my unheated garage. It is about 3’ deep and covered with a clear plastic molded cover that lets in light but is not airtight by any means. Last night we got down to 19.7 degrees F here in my backyard but in the window well it only dipped down to 36 degrees. Even though they are 3’ below ground level I can access them through a sliding window to check on them about once a week and give a little water as needed. And there is still enough air exchange so I don’t get any fungal buidlup. So don’t overlook unheated “natural” greenhouses like this for over wintering your small trees.

What do you do to deter rodents?

 

[Leo in N E Illinois]

To deter rodent I don't mulch around pots set on ground , until AFTER the ground freezes. By time ground freezes, rodents will mostly have made their winter homes.

Mulch early and rodents will snuggle up with your trees.

 

[WNC Bonsai]

To deter rodent I don't mulch around pots set on ground , until AFTER the ground freezes. By time ground freezes, rodents will mostly have made their winter homes.

Mulch early and rodents will snuggle up with your trees.

Not down here, we get them coming in the house every time there is a cold snap. I put out baited mouse traps in the basement and use VoleMax around my trees to deter them.

 

[Deep Sea Diver]

Mostly mice and rats prefer the compost pile… yet the wacky wabbits will munch on anything they find themselves in front of -Aargh!

Seem to esp. love young maples, hawthorn, JBP, JWP, Quince, azalea, occ. junipers, grape hyacinths and what ever!

Note to self: Get slingshot for Xmas!
(Whew - feel better now that’s out!)

Cheers
DSD sends

 

[leatherback]

You don't want your roots frozen long term, that's how branches dry out and die back. Being completely frozen also doesn't really count towards dormancy days. It's better to be cold than frozen, but then you have to water more often.

perhaps. but is is also not nice to see the roots fluctuate between 50F and 10F all the time

 

[rockm]

You don't want your roots frozen long term, that's how branches dry out and die back. Being completely frozen also doesn't really count towards dormancy days. It's better to be cold than frozen, but then you have to water more often.


What do you do to deter rodents?

Speaking from an area that can see strings of days in the teens followed a week later by days with temps in the 80s in winter, I'd prefer frozen. Freeze/thaw cycles are also hell on roots, as is very early growth that can result in a string of days over 50 in January, followed by aforementioned deep freeze. I'd kill for consistent winter cold.

 

[jimlau]

I had thought watering much during warmer days between freezing could be a problem, because the trees take in the water, then that water freezes in the trees and expands, doing damage. Seems not correct.

 

[WNC Bonsai]

They really don’t imbibe that much when the pot is frozen, however if the roots dry out they will die and so will the tree in spring. In additon as the water in a pot freezes it releases a small amount of heat which helps buffer temp changes. The same things happens with extracellular water. The cell cytoplasm is concentrated considerably and acts as something of an antifreeze. This is one of the physiological changes that happen as the trees prepare for dormancy.

 

[shohin_branches]

Speaking from an area that can see strings of days in the teens followed a week later by days with temps in the 80s in winter, I'd prefer frozen. Freeze/thaw cycles are also hell on roots, as is very early growth that can result in a string of days over 50 in January, followed by aforementioned deep freeze. I'd kill for consistent winter cold.

Michael Hagedorn would disagree with this. In Bonsai Heresy he talks about the unheated hoop houses they use in Japan when he was an apprentice in Nagano and the pots would freeze every night and heat up every day.

I personally keep a heater in my shed to protect my trees from severe cold

 

[rockm]

Michael Hagedorn would disagree with this. In Bonsai Heresy he talks about the unheated hoop houses they use in Japan when he was an apprentice in Nagano and the pots would freeze every night and heat up every day.

I personally keep a heater in my shed to protect my trees from severe cold

I guess I'm sorry that Michael Hagedorn disagrees in his book about unheated hoop houses in Japan. I live in Va. in a completely different climate with completely different conditions and tree species. I have been overwintering bonsai for a very long time. What I do works and works well.

 

[Bonsai Nut]

Michael Hagedorn would disagree with this. In Bonsai Heresy he talks about the unheated hoop houses they use in Japan when he was an apprentice in Nagano and the pots would freeze every night and heat up every day.

I personally keep a heater in my shed to protect my trees from severe cold

Nagano is zone 8B. If you have trees in a hoop house, I am surprised that they are freezing. An unheated hoop house provides about 10F of protection - and maybe more if it is a sunny location, has double plastic, etc. So it basically increases your USDA zone a full point to 9B. More importantly, it also increases daytime temps, and reduces the rate of fluctuation between days and nights.

But what can I say... I don't live there

 

[leatherback]

But what can I say... I don't live there

Me neither. 7A it is here.
This morning as I got up -5C / 24F. Thawing again now