I installed two 6' "cherokee princess" dogwoods for one of my residential customers last fall. This spring, one died pretty quick. I replaced it in July and it has been watered a decent amount (not heavily, though). Both are in good "dogwood" locations (near large oaks, scattered sunlight, etc.). Both have developed browning leaves mostly on the lower branches. Any ideas? Obviously, my first guess is insufficient water. The soil is a white clay for the most part. The hole was dug three times the pot width so there's plenty of room for root growth. The clay stays fairly soft since it was ground up by the auger. Thanks for any input.