winter protection zone 5

[newby]

Good morning! I'm sure this topic has been covered but nothing specific comes up on a search. I am in Ontario, zone 5a, winter temps regularly below-25C with varying amounts of snow.
I have several little native deciduous trees I'm growing along , and also several small evergreens. They are all young and in pots- how do I protect them in winter? I have an unheated greenhouse, but it can actually get pretty warm in there on a sunny day. We may be moving this winter so I can't stick them in the ground. What techniques do people use to protect these youngsters from freeze/thaw damage? I had thounght of sticking them in a styrofoam cooler filled with mulch. Looking forward to learning from the collective wisdom here!

 

[rockm]

Good morning! I'm sure this topic has been covered but nothing specific comes up on a search!
I have several native deciduous trees I'm growing along , and also several small evergreens. They are all young and in pots- how do I protect them in winter? I have an unheated greenhouse, but it can actually get pretty warm in there on a sunny day. We may be moving this winter so I can't stick them in the ground. What techniques do people use to protect these youngsters from freeze/thaw damage? I had thounght of sticking them in a styrofoam cooler filled with mulch. Looking forward to learning from the collective wisdom here!

Best post your location (state, province, etc) That is critical in providing overwintering advice.

FWIW, this video from one of the top U.S. bonsai professionals is a place to start. It's not specific to Zone 5, but if provides the basics to think about in overwintering most everywhere

 

[Colorado]

Also totally depends on the specific species. More information would be helpful!

 

[rockm]

Good morning! I'm sure this topic has been covered but nothing specific comes up on a search. I am in Ontario, zone 5a, winter temps regularly below-25C with varying amounts of snow.
I have several little native deciduous trees I'm growing along , and also several small evergreens. They are all young and in pots- how do I protect them in winter? I have an unheated greenhouse, but it can actually get pretty warm in there on a sunny day. We may be moving this winter so I can't stick them in the ground. What techniques do people use to protect these youngsters from freeze/thaw damage? I had thounght of sticking them in a styrofoam cooler filled with mulch. Looking forward to learning from the collective wisdom here!

If you fill out the user profile on the left of your screen, your location info will appear automatically in that window. Posting it in the body of a question only makes that info available once...

 

[dbonsaiw]

I had thounght of sticking them in a styrofoam cooler filled with mulch.

I was considering something similar. Basically, building a large box in which I can fit all my trees. Surround the pots with styrophome and fill in the spaces with mulch.

 

[penumbra]

I had thounght of sticking them in a styrofoam cooler filled with mulch.

I am actually going to build a large coldframe this year made out of construction foam. It will be right next to the foundation of the house.

 

[rockm]

I was considering something similar. Basically, building a large box in which I can fit all my trees. Surround the pots with styrophome and fill in the spaces with mulch.

If the box is out in open air and not sunk into the ground, this will be mostly useless. The trees inside will be at the same temperature as the air mostly. You are at the mercy of air temperature--the foam and box will trap warmer day temperatures, but that will dissipate more quickly than a cold pit or mulch pile which traps ambient and more stable ground heat. Additionally, the treatment can also work to your disadvantage-once the temperature in the box falls, the insulation will keep it there just like like warmer day temperatures. In the depths of winter, that cold can deepen and remain constant...

 

[August44]

Reliable winter protection should have a controlled heat source (heat matts and thermostat) and a regime for mold spray IMO

 

[sorce]

Only -13F!?

We've seen -33C here and I don't do anything but huddle them on the ground.

Never lost a tree to winter alone. Ever.

Even completely unprotected on 3rd floor window sills where at one point, there was an inch of ice built up on the inside of the window.

The more you think it, the more you sink it.

Leaving them in place until heavy frost dips end is key.
So is not repotting in spring.

Sorce

 

[penumbra]

There is no question that a coldframe partially in the ground is the best alternative for a cold frame. But my experience with cold frames on top of the ground in my climate has been excellent. The only loses I had this past winter were a few trees that should have been in one of my two cold frames but I ran out of room. Two crape myrtle that were not in the cold frames suffered quite a bit, in fact, one is in the burn pile. The ones that were wintered in the cold frames, unheated and not buried, did just fine. Same with my satsuki. The ones in cold frame and those in a non insulated white plastic hoop house did great. 3 of the 8 on top of the ground died although they were mulched in.
I know it was cold in these unheated unburied frames, but apparently the moderation of temperature swings is a lot more significant than the actual temperature. Also, because these frames were cold and unheated, there was no issue with mold or fungus. I agree that this is likely to be a concern in a heated cold frame.