Watering Irises Under Fruit Trees

I am going to be planting some TBs around the dripline of my apple, peach and nectarine trees. The trees have amended soil, but at the edge of the drip line, it turns to pure sand (as we're in a former lake bed and it looks like a beach here). The irises will probably get a little fertilization from compost run-off from the trees and maybe some low nitrogen stuff for "bulbs" through out the growing season. When the temps hit 105+, the trees get watered deeply 3, 4, sometimes 5 times a week because the sand drains so well. Also, watering also often happens at night because I don't come out of the a/c until temps get below 90! Average summer humidity is under 10%. If planted on little mounds of sand, do you think they could handle that much watering - especially from overhead? I am going to try some, anyway, but was curious about what you thought about that or if you had some ideas on doing it better. (My main concern is devising a way to foil the dogs - they think newly planted irises are great toys.) Thanks. Karla

Here in Tennessee we had to take down an unhealthy crabapple tree because it was making the irises below sick. Probably in NV your air isn't as humid though as it is for us in Tennessee. The crabapple leaves developed yellow spots all over them (fungal in nature I'm sure) that when it rained transferred down to the irises below. As soon as we took out the tree the irises started getting better. So now I avoid putting my irises anywhere near the fruit trees.