The plants that always need most of my attention and, in general, a lot of tough love - are the tomatoes.
They need to be constantly pruned, to have all branches that touch the ground removed, to have all leaves that even remotely look like they are sick cut, in oder to allow for air flow inside the plant. This is especially important in the South where it get humid and hot often.
It is especially hard for me to prune. I always want to save and help a plant. But it is important and probably the single most important thing to learn to do well, for tomatoes.