japanese maples frozen in pots

[Gilly]

Personally, I'd have these down on the ground with the pots mulched or insulated in some way. When I lived in zone 6 MA, temps in my unattached garage could fall into the single digits... all my trees where on the cement floor mulched with wood chips and did just fine. I monitored the temperature of the floor under the mulch and it always stayed at or above 32 F all winter. You will need to set out traps for mice and voles... juvenile maple bark and small branches are very attractive to them during the dead of winter.

I assumed that the cement would be colder cause it's not the dirt , also they are mulched with leaves and burlap and sitting on styrofoam , I put about 5 more in the ground

 

[Gilly]

Personally, I'd have these down on the ground with the pots mulched or insulated in some way. When I lived in zone 6 MA, temps in my unattached garage could fall into the single digits... all my trees where on the cement floor mulched with wood chips and did just fine. I monitored the temperature of the floor under the mulch and it always stayed at or above 32 F all winter. You will need to set out traps for mice and voles... juvenile maple bark and small branches are very attractive to them during the dead of winter.

I assumed that the cement would be colder cause it's not the dirt , also they are mulched with leaves and burlap and sitting on styrofoam , I put about 5 more in the

 

[Dav4]

I assumed that the cement would be colder cause it's not the dirt , also they are mulched with leaves and burlap and sitting on styrofoam , I put about 5 more in the ground

The cement is in contact with the ground, which is a giant heat sink. Pot's on the ground (or on the cement floor) will always stay warmer then the ambient air temps at night. Mulching them will provide further insulation.