Hydrangea 'Paniculata Grandiflora' (or P.G.), has white blooms emerging as elongated clusters of flowers that may droop from their own weight. The mature blooms gradually turn pink. Allowed to remain on the shrub, the blooms eventually turn a rusty brown.
Because of its size and ragged winter appearance, Hydrangea 'Paniculata Grandiflora' is better suited to be in the distance of your landscape. This shrub that can be pruned to a single leader to look like a tree. Pruning is needed to maintain height and width, whether as a shrub or tree form, since this hydrangea can reach heights of 25 feet.
Prune in the fall, late winter or immediately after blooming. Unlike Oakleaf, Mophead or Lacecap Hydrangea, whose buds show on old growth, Hydrangea 'Paniculata Grandiflora' produces buds on new growth. By pruning in late winter, you can see the season through with a well-manicured shrub or tree.
Cut branches randomly throughout to thin the shrub, if desired. This pruning technique will also yield larger, though fewer, blooms. Instead of thinning the shrub, prune only branches that extend outside the shape of the shrub or that cross other branches. Look for buds of spent flowers on the branch you want to cut, leaving a few on the branch.
Prune branches broken by weather or accidental encounters. The weight of ice from a storm, excessive wind or a wayward soccer ball may cause branches to break. Cut the broken branch just below the break.
Cut branches off the lower half of the trunk to create a tree-like appearance. Typically, the top of the shrub is pruned to a ball or gum drop shape. Hydrangea 'Paniculata Grandiflora' can be cut down to the ground if desired. Even if it had been pruned to a tree shape before cutting to the ground, it will grow back as a shrub.