I Thought Mint Was Unkilliable

I've been told by professional florists (from whom I was trying to buy plants) that my f'ng mint batch, bought in Oct., is dead, and granted that my Oct bunch of basil, repotted and watered every other day (like my dead mint) is struggling along, I'm starting to think that I'm not going to buck the trend.

But I'm willing to water my herbs every day (to combat the overheating); I have full light in the mornings; I have a very spare hand on the Miracle-Gro, and I am very willing to accept that my various indoor flowering plants should stop being exciting--but what I really want is a nifty way of growing indoor herbes for eating. Advice?