Any thoughts on the hardiness of St. John's Wort? We have an established garden with a large bed of St. John's wort. The previous three winters we have had in this home it wintered fine, with only the occasional brown leaf. This year with two spells of -10 or colder, our entire bed is brown and appears dead. I would say less than 1% of leaves are green, and those leaves there green all have some brown. Any thoughts if it will come back? Should I cut it all back? We generally don't do anything to it but try to keep it from expanding too much. Thanks for your help.
I'm assuming you're referring to H. calycinum (would be the common groundcover one)? The problem could be rust. Often managed by cutting back hard this time of year, and (if alive) will produce vigorous new growth and freshen up completely. Some people simply mow it annually. Given the symptoms, in case it's fungal/viral, clean up all the cut growth and dispose of.
