Becky, I am in the same 100-degrees+ summer as you and I try to grow mine with some kind of shade to shelter them from "too much" sun! Some can hide from the worst heat and sun by the side of our shed, some get a bit of help from some 5-foot shrubs, many are kept on or in the shade provided by a raised porch with lattice panels, and just as many are grown under deep shade trees.
The ones that grow in a larger garden plot that just gets no shade whatsoever usually go right into dormancy come July 1, and by the end of summer (about Sept-Oct) when I dig to rescue and/or divide, the roots and fans have pretty much reverted to seedling size and tenderness. Just too much sun and heat.
I am looking at ways to get some adjustable shadecloth over those that are out in the middle of unprotected garden - maybe run clothesline between the two ends of it (attach to fence on one side, shed on the other) with eyehooks to allow the cloth to be retracted. Even better, there are two-string retractable clotheslines that can afix to one structure and be pulled over (or retracted) that I could afix the cloth to (tuck-away shadecloth mechanism). I'd love to make some kind of awning that would be easier to just lean out and push back in, but so far have not figured out a way that would work in that particular garden area.
This year I am also trying to keep up with early watering, really soaking the unprotected beds, but even now they are drying out very quickly. I know it might also help to put those water-absorbing crystals under the roots, but I really want to avoid synthetic, artificial or assistive materials in the garden soil.
Will be interested in hearing how others achieve some protection for their high-heat/sun daylilies ... in our zones, the accepted wisdom about sun-loving daylilies can leave us with melting, bleeding, wilting, bleached out flowers that stop appearing as soon as the temperatures rise. What is more distressing is to see how battered the roots and fans get after the prolonged exposures.
On the other hand, I do now rotate my "best" daylilies to the "heat furnace" section of the garden to track their performance. Slowly but surely I am finding which of my best daylilies also have some real fiber to them - and it is sometimes quite a surprise which ones really benefit a garden the most.
