Study this plan slowly before you proceed. Rapid growth usually involves using nitrogen rich fertilizers, that is, fertilizers whose NPK Ratio has a large N Component compared to the PK Components. It also requires a "hungry" plant, like roses, that quickly react to fertilizer applications. Hydrangeas are not heavy feeders like roses. But applying this type of fertilizer can keep your plant in growth mode when it should be going dormant in the Fall. And if caught in growth mode by early frosts, the plant could be damaged.

Have you considered instead starting with a large shrub to begin? You could look for a plant nursery that sells large/tall hydrangeas. This would require directly calling the plant nurseries (or contacting a local landscaping company) because I do not recall seeing information about especially large/tall shrubs for sale in nursery websites.

Thanks luis_pr, this was the largest pruned Pee Gee in the area, and 4' is a good start. I was considering one application of nitrogen fertilizer during July, and only water til spring.

The nursery supported the branches with plastic ribbon,(similar to police tape but more narrow). If I remove it, I fear the branches will not be able to support the blooms.

Is it healthy to prune the blooms back to the bloom leafs to promote branch growth, and prevent branch breakage from the weight of the blooms?

"New" hydrangeas stems suffer from this problem (especially Annabelle) but the stems will get stronger as they age. You can prune PG at any time (well almost... if it is about to bloom, you might just let it bloom so you can enjoy the flowers).