Awww, tough lesson! I love our oak tree for it's shade but putting a bed under it was a mistake on my part. The pecan tree is wonderful to garden under 'cuz, of course, between the squirrels and people, hardly any pecans lay on the ground long enough to sprout. Live'n'learn, huh? Not all shade is created equally, LOL!
I'm really impressed looking at your pics again. That's what I do with annuals and you've done it with perennials. I don't think all of those particular plants could survive the heat here but man, I'm a fan of what you've done!