Willows can have roots above ground so I would steer clear of them. I have an ornamental crabapple which gives me no problem with roots and a very tall blue spruce. No problem with roots with the spruce but it does suck up any moisture that the daylilies need. I don't have any daylilies planted directly under the spruce but at least 4 to 5 feet away but they still suffer from moisture loss from the spruce. I have daylilies planted under the crabapple and they only get a half a days sun and they bloom just fine.

I find Maurice ' comment about growth rate of daylilies in different temps.very interesting. I tend to shy away from expensive evergreens because of the extreme cold they can face in the north. Prolonged heat isn't something that we face very often so I can't relate to what all you hot weather gardeners face.

Have you found that it takes a curtain peak temperature or period of time to cause your flowering plants to give up? I also understand how frustrating it must be to those under water shortages or bans.l would think that many of you have come up with unique or different ways of combating hot growing conditions. I will says that some of the pictures from yours gardens are outstanding and show your love of gardening.
Chuck