I've only just seen this post. I left mine in an unheated greenhouse and the same happened. I've cut away the flower heads and am now left will a sad looking trunk/main stem. Kicking myself for not bringing it indoors, as it happened to the same plant the previous year. But it grew back after I cut back the dead flower heads and when the weather got better I put it back out side and it came alive.
I hoping that it will happen again in late spring when I put it back outside.
Posts
I've cut away the flower heads and am now left will a sad looking trunk/main stem. Kicking myself for not bringing it indoors, as it happened to the same plant the previous year. But it grew back after I cut back the dead flower heads and when the weather got better I put it back out side and it came alive.
I hoping that it will happen again in late spring when I put it back outside.