Tried to space a hydrangea row kept getting my wires crossed need some help. Called a trusted nursery to see if my spacing was correct and got some odd info. The shrub manager advised planting hydrangea like Endless Summer a normal 4'X4' shrub. He advised measure 4' from the center of the plant in all directions, do the same for the next shrub, eight feet from root ball to root ball?

The way I have always spaced hydrangea was to split the difference 4'shrub 2' every direction add a foot if you do not want the hydrangea to touch. Planted a Japanese maple today and they really do mean six feet in all directions canopy is huge. What is the correct method to get a two foot gap in a row of 4'x 4' ES hydrangea?

Where do you start the measuring tape side of the root ball or split the mature spread?

Need the gap; plan to add tall Asiatic lilies behind the hydrangea. They will need some sun to get the going each year don't want the hydrangea to shade them out.