At the start of the growing season/right before summer is not a good time to transplant any flowering shrub. Best to do so in fall as it enters dormancy or in late winter/early spring before its starts pushing new growth. And a 20 y.o. hydrangea is generally of a rather significant size and will be difficult to move regardless of timing.......just how big is it?

It is not large/huge in fact, I would say that it is on the smaller side of big. It's about 3.5' tall and of manageable girth. I think I could move it with one other person for stability and to help with the lifting. It's a size that I am sure I could handle.

Sooey

I have moved 2 lace caps from the sunny side yard of our house to the more shaded front part. I waited until Fall to move them. They have bloomed, they are getting ready to go dormant. It is just a better time to move them. I tied up the branches first in jute and then wrapped them in burlap. Makes transporting them so much easier. Had a nice big root ball and watered them in well at the new location. Took off the wrappings and watched and watered. I mulched heavily and wrapped them with burlap again come Winter, just to give them a bit more help to survive our Maine winter. Still going strong 4 years later. They are about 4' tall.

A third vote for early fall.

Thanks, Everyone,

I have made the decision to wait until the fall. I have the location all marked and will take action when it goes dormant.

Thanks, everyone, I appreciate your input.

Sooey