I have an only HATE relationship with a couple of plants - Japanese knotweed and creeping bellflower (there are several varieties) most adamantly. So I can't say those are love-hate relationships, only hate.
For me coneflowers fall into the love-hate category. They are long-blooming and supposedly easy to grow. I can't grow 'em. Rabbits like to eat them; the leaves often look bad; virtually all of mine got aster yellows two summers ago, and they often do not thrive for me, and I think part of that is because new cultivars are released that just don't do well. The one exception to this, assuming they do wel lthis summer, is Raspberry Truffle. That one seems to work.
Daylilies are definitely in the love-hate category. They are lovely when in bloom. They hold soil on slopes well. But I find them to be high maintenance; they often look very sloppy and need a lot of cleanup time. Some are in bloom for a very short time. When they aren't blooming, they are uninteresting. The orange ditch lilies are another story - don't love them at all. The previous owner of my home planted them all along the garage. I have managed (barely) to keep them contained there, but one of these days I'm going to dig them all up. And I think Stella's are very overused, so I don't care for them any longer.
Iris are stunning when in bloom, but that time is short. I haven't managed placement of these very well because the foliage is in the way and I don't like the way it looks after the bloom time is over. Same with tulips. I am half an inch away from pulling all of them out.
Campanula (all zillion varieties of them) are beautiful, long-blooming, and easy to grow. The hate part is that they require deadheading to bloom continuously. I had a lot of them and decided I was spending too much time deadheading, so I reduced my stock to just a few.
Joe Pye weed - I needed something big to block my view of the alley and neighbors' trash cans. It worked, It's pretty, it's a great butterfly magnet, but now it is reseeding itself everywhere, and it's gigantic, and it's quite tough to dig up. Anyone have a backhoe I can borrow?
Anise hyssop 'Blue Fortune' - I LOVE this plant, but....it's supposed to be maybe around 3 feet tall. I planted one in my daughter's yard, and that's how big it is, and it's just wonderful. When I planted it in my yard, it grew to 5-1/2 feet tall, and was much too big for where I put it. I've tried two or three other spots, and the same thing happened. Frustrating! It would have been the perfect plant for my corner, but it was so big that you felt like you were going to be attacked by it when you walked by.
