I transplanted a thriving little lilac shoot from Seattle, WA to my new yard in St. Louis, MO. Since the soil is clay in St. Louis, I was careful to amend the soil and followed the process for planting recommended by websites. The plant is a shoot from a rare, deep purple (almost black) lilac. It looked great in Seattle and also in St. Louis until a couple of weeks ago. The leaves turned brown and fell off - all of the leaves. All of the posts on this site and the websites I have researched say brown leaves mean the plant needs water. However, we have experienced so much rain in St. Louis that I think I am living in Seattle again - so much that we have made the news for storms and floods.
I am wondering if the plant is suffering from too much rain. I have another shoot from the same lilac planted a few feet away. It still looks good but it is planted a little higher than the one with no leaves. The other difference is that I ordered some mulch and the guys dumped a pile of mulch near the plant with no leaves. (I have not checked the branches to see if there is any green under the bark. I am afraid to look.) I am wondering if the roots have stayed too wet.
My question is: should I move the plant now (June 27) to higher elevation or wait until it gets cooler? Should I just wait to see if it will recover?
One other detail - a new Kousa dogwood tree from a nursery also looked good until a couple of weeks ago. The same thing happened to it. The leaves were green and then they curled up and turned brown. I have looked at both plants - no sign of insects or diseases.
Thanks for any ideas!