Thank you Newt - the Lilac bush is in a large pot.
We will look at the roots again to see if the roots need to be loosened
since in our haste to repot this may not have been done prior to being
repotted. Also we will keep this bush moist rather than waiting until it
becomes dry.
You are very welcome! You mention it's in a large pot. Sometimes when the pot is too big for the rootball there is the risk the soil will stay too wet or the rootball will dry out too much before you water. Another possibility is the surrounding soil might stay wet while the tightly bound roots dry out and you wouldn't know. A pot should be about 2" larger then the rootball.