Overwintering in Zone 4b/5

[kmaho]

Just starting to collect some trees and get into bonsai and already starting to think ahead to winter so I know I have plenty of time to get prepared. So far all of the trees I've gotten are hardy to my zone in the Minneapolis, MN area (well, the trident maple is iffy depending on if we have a 4b winter or a 5 winter...); however, I'm in a multilevel townhome and my trees are up on a small second story deck and I worry a bit about the extra cold that'll come from no ground below them. It's also a south facing deck getting full sun during the day. Since I just started here in the last few weeks, I've missed repotting season and everything is still in nursery pots and soil if that makes any difference.

Any suggestions for overwintering everything? I could build a cold frame in the garage for dead of winter I suppose but moving them in and out during fall/spring overnight temperature swings will be a challenge I suspect. I could build a simple frame for the deck and mulch them into there together but otherwise leaving them exposed to the elements?

 

[Attmos]

I can't offer any advice, but I wish you luck with them.

 

[Zac]

I believe on the ground would be best. Mulching in is done to use the consistent temp/warmth of the ground to protect the trees roots from the temp swings. Mulching in on the deck I don't think will do much. The garage is your best bet.

 

[Jrmcmich]

assume not too many trees yet but assume with your winters garage might work best but wonder if you have ever monitored garage temps before during winter? I have 2 separate garages both attached to house amd one gets cold in winter and hot in summer. Other stays relatively decent all year and was too warm over winter but that’s in Ohio. You would have to water trees in garage probably weekly or every other week. You could transition to cold frame in late spring if temps get too high in garage? I would Buy a temp gauge to monitor regardless where you decide to keep to see how temps behave in chosen environment

 

[rockm]

A general rule for overwintering is to prevent/minimize air circulation around pots/rootsOn an elevated deck you will have extreme difficulty conserving relative warmth (the object in overwintering is NOT to keep roots “warm” but cold enough to keep tree dormant and warm enough to prevent damage.)

Your deck will freeze pots more quickly and thoroughly and possibly kill roots. That’s because of the same all around air circulation that causes roads in bridges to freeze before surface roads. If you’re in a very cold winter you could definitely lose the trident and even some native species. Roots on native species in the woods are in the ground and the ground stays relatively warmer than air temperatures in winter.

I’d look for somewhere on the ground in your yard to mulch trees I and/or a ln unheated building like a garage to atore trees this winter.

Best

 

[kmaho]

assume not too many trees yet but assume with your winters garage might work best but wonder if you have ever monitored garage temps before during winter? I have 2 separate garages both attached to house amd one gets cold in winter and hot in summer. Other stays relatively decent all year and was too warm over winter but that’s in Ohio. You would have to water trees in garage probably weekly or every other week. You could transition to cold frame in late spring if temps get too high in garage? I would Buy a temp gauge to monitor regardless where you decide to keep to see how temps behave in chosen environment

Oh, I never considered that it might not get cold ENOUGH in my garage.... I am sandwiched between two other units so it may not hit that low to mid 30s sweet spot even though it's not a heated garage. I'll definitely get something in there to measure the temperature this winter but didn't last year since this wasn't on my radar.

A general rule for overwintering is to prevent/minimize air circulation around pots/rootsOn an elevated deck you will have extreme difficulty conserving relative warmth (the object in overwintering is NOT to keep roots “warm” but cold enough to keep tree dormant and warm enough to prevent damage.)

Your deck will freeze pots more quickly and thoroughly and possibly kill roots. That’s because of the same all around air circulation that causes roads in bridges to freeze before surface roads. If you’re in a very cold winter you could definitely lose the trident and even some native species. Roots on native species in the woods are in the ground and the ground stays relatively warmer than air temperatures in winter.

I’d look for somewhere on the ground in your yard to mulch trees I and/or a ln unheated building like a garage to atore trees this winter.

Best

This is what I'm worried about on the deck and why I was wondering if building either effectively a raised garden bed to be able to pack dirt/straw/whatever insulation around the roots or else a full cold frame with some insulated panels on my deck would be enough. Sadly, I'm in a townhome surrounded by concrete, no yard or any outdoor space to put them aside from my deck. This is definitely an issue and why I'm looking to try and find solutions here at the beginning of summer so I have plenty of time to brainstorm and build whatever needs building.

 

[rockm]

Oh, I never considered that it might not get cold ENOUGH in my garage.... I am sandwiched between two other units so it may not hit that low to mid 30s sweet spot even though it's not a heated garage. I'll definitely get something in there to measure the temperature this winter but didn't last year since this wasn't on my radar.


This is what I'm worried about on the deck and why I was wondering if building either effectively a raised garden bed to be able to pack dirt/straw/whatever insulation around the roots or else a full cold frame with some insulated panels on my deck would be enough. Sadly, I'm in a townhome surrounded by concrete, no yard or any outdoor space to put them aside from my deck. This is definitely an issue and why I'm looking to try and find solutions here at the beginning of summer so I have plenty of time to brainstorm and build whatever needs building.

I am in USDA Zone 7 so I don’t get really brutal winters. We do get occasional deep cold in the single digit sand even sub zero. It doesn’t last long though

I have a three foot deep cold pit dug into the ground that trees are placed and their roots/pots are mulched under a foot of shredded hardwood

I also place other trees on the surface of my brick patio then mulch them under more than a foot of mulch. Mulch is piled up and over the tops the pots reaching at least eight inches deep on the tops of the pots. The mulch traps ambient ground heat and keeps roots moist (dry roots in freezing conditions are dead roots.) Water insulates them. The mulch freezes through after a few days of below freezing air temps. That can take longer if there are warmer days. Frozen roots are not a bad thing as long as low temps in the root zone doesn’t get below 15 F or so.

Might not work for you in zone four but something to think about