PeeGee Hydrangea Shrub or Tree

Not Trees, but Pretty Close

A Peegee hydrangea that has been trained to look like a "tree."
David Beaulieu

PeeGeed hydrangea (H. paniculata 'Grandiflora') are flowering deciduous shrubs that grow quickly and very tall. So tall, in fact, that they are sometimes pruned to look like trees and have earned the nickname "tree hydrangea" These easy-care bushes are native to Japan and China and can be grown in USDA plant hardiness zones 3 through 8.

Taxonomy and Plant Type

Plant taxonomy classifies PeeGee hydrangeas (or P.G.) as Hydrangea paniculata 'Grandiflora.' This is a case where the botanical genus name (Hydrangea) is so commonly used that it essentially doubles as a common name. 'Grandiflora' is the cultivar name.

The species name, paniculata means "panicled" and refers to the shape that the bush's flower heads assume. In fact, you will occasionally see the bushes referred to as "panicle hydrangeas." A "panicle" is defined as a loose, diversely branching flower cluster. The cultivar name, too, is based on what the flowers look like: 'Grandiflora' means "large-flowered."

Also in the panicled class (that is, types of H. paniculata) are the following varieties (all are cold-hardy to at least zone 4):

  • ‘Limelight,’: Grows 6 to 8 feet tall and 5 to 7 feet wide and has a greenish color in its flowers
  • 'Big Ben': Grows 6 to 8 feet tall and 5 to 7 feet wide and is valued for having flowers of a deeper pink color than do most kinds of H. paniculata
  • Bobo: The dwarf type, growing only about 3 feet tall and wide
  • 'Pinky Winky,': Grows to a maximum height and width of 8 feet and is known for its bicolored flower heads (pink on the bottom, white on the top)

Characteristics of PeeGee Hydrangea

PeeGee hydrangeas will grow anywhere from 10 to 25 feet in height. Exact height and spread will depend on pruning and growing conditions. These are fast-growing shrubs, able to put on 2 feet in height under the best of conditions. They come into flower in mid to late summer.

The large, cone-shaped flower heads (or "panicles") are widest where they meet the stem and taper down from there. They contain white "blooms" that are actually mainly sterile sepals (petal-like plant parts). As such, they last much longer than true blooms. The flower heads take on a pinkish color over time before fading to tan or brown for the winter. A typical panicle may be 9 inches long and 7 inches across at its widest point.

In addition to their prodigious growth, PeeGee hydrangeas are known for their large flower heads (which last a long time) and their time of bloom. They bloom later than many shrubs and trees, allowing you to achieve uninterrupted sequence of bloom; that is, staggering blooming periods in your plantings so that you have flowers to admire for much of the growing season.

Growing and Caring for PeeGee Hydrangea

Grow PeeGee hydrangeas in full sun in order for them to flower best. The soil should be well-drained and enriched by organic matter. A soil pH that is slightly acidic is ideal.

PeeGee hydrangeas bloom on new wood. If you are looking to shape them, you can prune in late fall, winter, or early spring without the danger of losing the buds that will become the next crop of flowers. Fertilize the plants in summer with compost.

You can control the size of the flower heads on panicle hydrangeas, to some degree. If you want larger flower heads (as most people do), thin the plant down by pruning it so that it will have fewer main branches. This will result in fewer, larger flower heads because all of the plant's energy go into making fewer flowers.

If you train your plant to become tree hydrangeas, they will make fine specimens. In shrub form, PeeGee hydrangeas can be used in a hedge. These bushes work well in woodland gardens and cottage gardens.

Turning a PeeGee Hydrangea Into a Tree

PeeGee hydrangea plants, although multi-stemmed shrubs by nature and by classification, can be pruned so as to have a single trunk, thereby becoming, in popular lingo, "tree hydrangeas." If you have a hydrangea bush that you would like to train to be a hydrangea tree, begin the process in spring by selecting the straightest stem. This stem will become the trunk of the tree hydrangea.

Prune out the other stems (and continue pruning them out in future years). Stake the selected stem to provide temporary support. In future years, prune your hydrangea tree so that its branching pattern will conform to the desired shape and dimensions. This usually involves pruning off lower growth and encouraging a rounded canopy.