If the landscaper is a professional, then he will know how to go about transplanting the hydrangea......the main point is to get as much of the viable root as possible and burlap it for the transport......amend the soil before replanting and keep it moist until freeze up.

Ian

I would cut it back very hard to the crown of the plant and then dig it up. Keep as much of the soil on the roots as possible and move it to the new location as soon as possible. Plant it at the same depth and water it in real well and keep it wet and shade it if possible. It should be ok.