PeeGee Hydrangeas

Not Trees, but Pretty Close

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

Plant Type for PeeGee Hydrangeas

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; when used as a common name below, the first letter of the word is not capitalized. 'Grandiflora' is the cultivar name.

PeeGee hydrangea is spelled in a number of other ways, including Pee Gee (two words).

Writers are also at odds when it comes to whether the P and/or G should be capitalized. But people generally agree that the "P. G." could just as easily stand for "pretty good," as these bushes are quite useful to have in one's landscaping.

H. paniculata 'Grandiflora' plants are flowering deciduous shrubs. You will also hear "tree hydrangea" (or "hydrangea tree") in reference to this plant, because it can be pruned so as to have a single trunk (that is, you can train it to be a "standard"; see below) or just a few large trunks. Pruning it in this fashion allows you to accentuate a tree-like canopy.

Traits, Origin, Zones for PeeGee Hydrangea Shrubs

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 some years 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 will 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.

These bushes can be grown in planting zones 3–8. The species plants are native to Japan and China.

Sun and Soil Needs, Best Traits

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 preferred.

These three features are the most outstanding for PeeGee hydrangeas:

  1. Large flower heads.
  2. Ability of the flower heads to last a long time.
  3. Time of bloom.

Regarding these two last points, note that, because they bloom later than do many shrubs and trees (and because the sepals last for so long), PeeGee hydrangeas give you a chance 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).

PeeGee Hydrangea Trees (Tree Form)

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.

Care (Maintenance Pruning), Uses in Landscaping for PeeGee Hydrangeas

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. That is, 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.

The result will be fewer flower heads. But because all of the plant's energy will be going into making flowers on the branches that you have left alone, the resulting flower heads will be bigger.

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.

Meaning of the Name, Hydrangea paniculata 'Grandiflora'

Why all the variant spellings for "PeeGee" hydrangea plants? And how did they come up with a name like "PeeGee," anyhow? "PeeGee" is short for paniculata 'Grandiflora,' this hydrangea's species name and cultivar name. Technically, then, "p. G." would be perhaps the most sensible spelling. But, at some point, people decided to get cute and turn the abbreviation into a word (or two words, for those who prefer "Pee Gee"). So it is no wonder one now sees the name spelled in so many different ways.

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 (all are cold-hardy to at least zone 4):

  1. The popular ‘Limelight,’ which stays more compact (6-8 feet tall, with a width of 5-7 feet) and has a greenish color in its flowers.
  2. 'Big Ben' (also 6-8 feet tall, with a width of 5-7 feet) is valued not so much for being big as for having flowers of a deeper pink color than do most kinds of H. paniculata.
  3.  The dwarf type, Bobo (for those who truly own but a small space in which to grow one of these bushes). 
  4. 'Pinky Winky,' which grows to a maximum height and width of 8 feet, is known for its bicolored flower heads (pink on the bottom, white on the top).