It has definitely been a horrible winter for a lot of us and if it survived through this years winter in Iowa it is not a weak cultivar.
You may try moving it to a different bed sometimes I plant them and they just sit there and do nothing, so I move them around to a different spot in the yard and it takes off and does great. At least you will know it is hardy coming from here we had many 100 degree days in July and -55 wind chills in January if a plant lives through that it should do well just about anywhere.