Only seems noticeable on groundcover. Won't say others never get it.

H. androsaemum and x inodorum cultivars are also prone to it. One of the reasons we no longer sell Hypericum at the nursery....not much sense in promoting the planting of excessively problematic plants.

One of those last two has also been seeding out into local woods a bit, as well.

What about Hypericum X moserianum? Is it also prone to rust?

This is the second year for my hypericum moseramum/St. John's Wort. Last year, I thought it looked terrible with all the rust. So far this year, it looks great, but is only about a foot tall so far. Will have to see.