I planted two hydrandeas for a customer of mine about 2 weeks ago. They are wilting now. The other plants that I planted are looking really good. They are in full sun. The soil there is basically concrete, so I dug some big holes and filled them with soil/compost mix. I've instructed them to water them which they said they have been doing. I watered them myself yesterday. I haven't been back to see if they've perked up. I was thinking that maybe they didn't water them enough, so I watered them really well. I also clipped the dead leaves. How can I save these plants? Thanks for the help.