they can survive a minor frost for a very short time but will stop all growth at the least. heavy frost means certain death without a chance for revival. plan on an end of sept harvest up there no matter if they're mature or not. leaving them go thru a frost and death will affect the flavor and not in a good way.

there are strains around that will finish in time for your area that are worthy of your time and space. check out some dutch passion durban poison or any of the 'early girl' varieties. some bb crosses will also work and put out some fine bud...stay away from sativa-doms and look for the straight indi's like an afghani...most of those canadian strains should also work. klozit king can help ya with that...

good luck