Bare Root PeeGee in need of height not width

[Tvthyme]

Hello Hydrangea-philes - I am in need of help with a bare root PeeGee hydrangea. I've had the tree in the ground for 3 years and it is growing wide, flowering, getting plenty of leaves and sun. My problem is, the trunk of the tree is only 2-3 inches out of the ground and the stalks/leaves are massive. Although it's a tree, it's growing like a shrub. I trim it after it flowers, fertilize with slow release and coffee grinds but can't seem to get any height on the trunk. Should I cut it back now and bind the branches up for the winter so the tree will grow Vertically?

Any suggestions are welcome
thanks