[I originally posted this in the perennials forum, but copied it over here. ]



I'm fairly inexperienced with this plant. I have two specimens that have been planted in ground for two years now. One is sporting new healthy spring growth and small blooms, but the other one, planted just a couple of feet away, has no new growth, smaller and drier looking blooms and the leaves look like they're infected with rust. Any ideas as to why only one of these (originally identical) plants would be ailing?

The one sporting the rust spots gets more direct sun than the healthier plant. Too much sun, maybe?

Is this plant an exceptionally heavy feeder?