I think every gardener comes across a plant species that they simply can't grow. For me, it's clematis. Its been carrying a grudge against me for years. That is until I stopped trying so hard.
I was intimidated by clematis during my early years as a landscape grunt. Don't break the stems while you plant it! Plant it deep but not too deep! Make sure the roots stay cool! Don't prune it the wrong way or it won't bloom!
I planted clematis armandii several years ago (you know, the evergreen one with white flowers) against my porch at the time so that it would drape over the top of the porch. Well, it didn't do anything. It looked okay, but it never grew. Year after year--it grew only a few inches. I moved and drove by it last month and it still looked the same.
I planted many clematis for my former employer and they did the same thing. They looked okay but they didn't grow! I know what you're thinking, I didn't plant it right. Too much clay soil, blah blah. I did plant it properly. It just doesn't like me.
My garden designer friend Patrick has a similar story. His nemesis is rock rose or cistus. Rock rose, you say? Easy stuff, it grows like a weed and it doesn't require or even like care. Now this is a guy that's designed most of the McMenamins gardens (and many more) so let's say he knows what he's doing and his gardens are awesome. But according to Patrick he can't get his cistus to thrive or even stay alive. Go figure, maybe he pissed off the rock rose spirits at some point in his reckless youth.
So my point? Do I have one? Yes. Some mysteries can't or even don't need to be solved. If you don't have success with certain plants move on! Don't be a drama queen about your inability to grow your favorite flower. I think you're lying anyway if you say you have a favorite flower. How could you possibly choose just one? There are a gazillion plants to choose from and you'll never get to all of them.
Oh, by the way. I picked up a discount clematis last spring. It looked depressed and lonely and since I'm a sucker for a sad sack and a sob story I plucked it off the table and tooled home with it in my truck. What the heck, I thought as I carelessly potted it and shoved it onto the corner of my balconey. I watered it-that's about all-and guess what? It grew, it bloomed, and now-a year later-it's growing like crazy. Haven't done a darn thing to it and it's growing in a small pot in old soil.
Oh, don't get all weepy on me. The curse still lives on--I lost the tag and I can't for the life of me remember the name of the bloody plant.