My Varigated Hydrangea is about 6 feet tall in the shape of the letter V, but it has stalks shooting out everywhere of different lengths and looks rangey.

One year I tried to prune all the top branches to uniform height, and many broke out in rampant growth upwards, and it looked worse than ever.

I would like a uniform mounding shrub if possible. So how do I encourage bottom side growth to make the plant fuller and keep the top level. Do I need to let it grow to its maximum height, which appears to be over 6 feet tall, before I prune the top in a sloping contour?

I don't care about blooms. It is under oaks and I appreciate the foliage.

I've been trying to shape these shrubs unsuccussfully for several years, so any answers are appreciated! Thanks.