Sounds to me like too much mirical gro...
Pinch the sedum and the cosmos about mid june...that should help with the flopping.
And day lilies do look a bit ratty this time of the year....but they will make big clumps faster if you don't cut off the leaves and force the plant to make more leaves instead of growing and storing energy in the roots.
Linda c

You have a very special cosmos plant that will reward you with 100's of flowers in September. I always pulled them out, thinking they were overgrown, flowerless monsters, but one year I let them grow and was amazed at what those plants produced. So stake them up as best as you can and just wait for the glorious show.

As for the sedums, put a peony ring around them in early spring, before the stems grow up through them. You will have a lovely plant.

Enjoy!