Your astilbes and columbines may have just gone dormant until cooler weather. I often have to cut mine back to the ground from lack of rain, but they usually either regrow in fall or the next spring
. The azalea, however, may not regrow new leaves...they are extremely sensitive to drought because their roots are shallow. I think your Japanese Maple will recover as well. Columbines are very easy to start from seed
, so if you have any seeds
, you can start them now and by fall they'll be ready to plant. That way even if you lost some from the heat you can replace them. I have lost several of the perennials that I planted this spring
because of the drought. So I've been trying to replace them with more drought tolerant plants, like agastache and sedum. There are quite a few different sedums with different heights, flower
color and leaf color, and they don't require a lot of water. It can be hard to find shade plants that are drought tolerant, though.