Both James Beattie and Simon Rickard (gardeners of excellence!) confess (in the comments section of Simon's guest blog post on Marlborough daisy) to killing plants while pondering - sometimes over years - where exactly to plant them. I have to actively suppress thoughts about the plant carnage that stains my horticultural history. Even right now, I'm in the process of killing Itea illicifolia, Kerria japonica (the single flowered form), Lonicera fragrantissima (that I lovingly propagated from cuttings about a decade ago), and a pot of seedlings of Malus toringoides (pictured). I'd love to know what you've killed while trying to decide the place in your garden where they would be happiest!