My zone Rocky Ford Colorado is listed as a 5b.. which is -15 below and it's not hadsn't been for many years.. I lost everything my first winter here at 35 below winter temps.. on average we get -25 below winter temps every year..we treat our backyard perrennials as zone 4 when planting.. I've had more success planting for a colder winter.. My whole espalier orchard is zone 3 and 4.. You need to rethink and recalculate growing zones .. most are no longer ACCURATE
My zone Rocky Ford Colorado is listed as a 5b.. which is -15 below and it's not hadsn't been for many years.. I lost everything my first winter here at 35 below winter temps.. on average we get -25 below winter temps every year..we treat our backyard perrennials as zone 4 when planting.. I've had more success planting for a colder winter.. My whole espalier orchard is zone 3 and 4.. You need to rethink and recalculate growing zones .. most are no longer ACCURATE