I live in PA. Last fall, after reading your article on pruning a butterfly bush, we cut it back to about 1 foot or so. This spring/summer. . . . nothing. We did cover it with mulch over the winter. Is it dead? Should we replace it? We just moved into our home and the bush was there; therefore, we don't know how old it is or how it was taken care of. However, when we moved in last August, it was blooming beautifully and there were a lot of butterflies on it.
This late in the season, the plant is likely dead. But, to be sure, you can dig up a little of the rootball and check the roots. Living roots will be pliable and firm while dead roots will be brittle or mushy.