Q: This hydrangea is a volunteer that appeared last spring by our deck on a newly built house where the lot was graded. It bloomed nicely this year but the size and color of the leaves concern me. Why did it bloom in two phases?
A: It looks to me like the roots on the smaller side are not very healthy, probably from construction damage. This could explain why the leaf sizes and flower colors are different. Damaged roots can’t absorb the minerals needed to create flower color.
This fall, take it up, prepare the soil properly and replant.