Cold frame - balcony / terrace


I have south-east facing balcony with roof (sun from morning until around 2PM) and a south-west facing terrace (afternoon sun).

In first winter i have put my three small trees inside styrofoam box and i have placed the box on the balcony by wall.

Now that my collection is started to expand, styrofoam box is not a solution anymore, i am considering a cold frame that i could assemble in the winter and place it on the terrace or balcony.

Does anyone have any experiences or advice regarding this?


P.S. I have the tools and enough know how to build it myself, given the right amount of info.


Hey @MarkoB

I just read your post and the next winter is coming very soon.

I cut a shelf from the Swedish company in half and wrapped it with bubble plastic for my descidous trees.

Probably that helps for the upcoming winter.

For all my trees I put them in my unheated garage for the winter, or I bury them in my garden frames. However I have a large Japanese Willow in a pot that is too big for either option. What I did last winter was wrap the pot in reflective insulation. The tree survived beautifully. See picture.

Bob! Your name tag doesnt say where you are. Is it cold enough there for winter worries? What winter temp is the willow good for? Arctic willow will take -20F happily…
On the ground up against a north wall out of the wind.
Maybe wrap the main trunk with the insulating paper wrap. Maybe bubble wrap the top and pot. Duct tape. I like the reflective type. Looks odd, but is effictive. Mini greenhouse. Would need to be out of the sun.
I use a 2x6 ramp. Slide it on wood to a safe spot out of the North wind… my largest tree in a bonsai pot easily weighs 80+ lbs. Can’t pick it up or set it down.
Will a 50 gallon garbage can fit over the whole thing? Tie it down… I’ve used 5 gallon buckets in real bad winters.
I would put that puppy into a small bonsai pot! Trim and wire! (Start me a half dozen cutting slips…!)
I had an arctic willow. It did NOT like the heat/dry here…

Hello Marko,

one issue you need to be aware of is the sun heating your protected area up during the day and then the cold/freezing temperatures go back in during the night. Otherwise you should have god protecting against wind at the balcony.


I’m in southern Ontario Canada. It got to -20c here last winter. The willow survived without issue. The inside of my unheated garage got down to -10c during that same 2 week period. I lost one Hokkaido Chinese elm to the cold in the garage.