Knowing the type of hydrangea you have goes a long way in knowing how to care for it properly— from sunlight, watering, and fertilizer requirements to when, how, or if to prune. Different varieties have different needs. When you know the type you have, you can quickly learn how to help it thrive.
When you buy a hydrangea, it should come with a plant tag that tells you the plant’s name, both scientific and common, its mature size, and its cultural requirements. Without that knowledge, you could jeopardize the reason we grow them – those big, beautiful flower clusters. So study and save that plant tag!
But maybe you’ve recently moved into a new home with hydrangeas in the garden. Or perhaps the plant tag is lost. How do you know what type you have?
There are ways to identify these shrubs by looking at the growth habit, the size and shape of the plant, the leaves, and the shapes and colors of the flowers.
How to Use This Guide
This guide starts with the easiest hydrangeas to identify. By answering a few simple questions and through the process of elimination, you can narrow down the choices. Sometimes differences are subtle, so you’ll need to be a bit of a detective.
If a hydrangea has been improperly pruned or hasn’t been given the proper care, it may be challenging to identify. And it might not be in leaf or in flower when you want to identify it.
So there are several identifiers to help you.
The names of some of the more common cultivars are also provided. Someone might tell you that you have an Annabelle or a Tardiva. “Annabelle” and “Tardiva” are cultivar names, not types. But knowing the cultivar can help you nail down the type.
1. Growth Habit
First, look at the plant’s growth habits. Is it climbing up a wall or a tree? Mounding over a low stone wall? This one is easy – it’s a climbing hydrangea.
Hydrangea anomala (formerly H. petiolaris)
Common name: Climbing hydrangea
USDA hardiness zones: 4 to 8 (native to China and the Himalayas)
Size and shape: Climbing and mounding, 30 to 50 feet over many years
Growth habit: Slow-growing, woody vine
Leaves: Glossy green, slightly rounded
Flowers: White lacecap, blooms on old wood
Cultivars: Firefly, Miranda
Other ID features: Tiny rootlets on the woody stems attach to trees and walls, dried flower heads can persist through late winter
Next, look at the shape. Most hydrangeas are rounded or upright shrubs. One type will stand out from the rest in this regard—oakleaf hydrangea. It’s easy to recognize with its suckering habit, exfoliating bark, and oak leaf-shaped leaves.
Common name: Oakleaf hydrangea
USDA hardiness zones: 5 to 9 (native to the southeastern United States)
Size and shape: Rounded, 3 to 6 feet tall and wide, depending on the cultivar. Suckers can create a thicket over many years.
Growth habit: Coarse textured, rounded shrub with a moderate growth rate
Leaves: Shaped like an oak tree leaf which turns red, orange, and purple in autumn
Flowers: White cone-shaped flowers on long panicles fade to a pinkish brown; blooms on old wood
Cultivars: Alice, Ruby Slippers, Jetstream, Pee Wee, Snow Queen
Other ID features: Stems have peeling bark
How large is it? H. macrophylla, H. seratta, and H. arborescens all grow between 3 to 6 feet in height, but H. paniculata grow to 10 feet or more. H. paniculata also has cone-shaped flowers, while the others have mophead or lace cap flower heads.
Common names: Panicle hydrangea, PeeGee hydrangea
USDA hardiness zones: 3 to 8 (native to China and Japan)
Size and shape: Up to 10 feet tall and wide; sometimes pruned into a small tree. There are dwarf cultivars that only get 2 to 3 feet tall, so if your shrub is small, but you think it might be H. paniculata, look at the leaf nodes.
Growth rate: Moderate
Leaves: Toothed, three leaves per node (the place on the stem where the leaves come out is a node)
Flowers: Large, cone-shaped flowers in pink, white, purple, blue, or green depending on the variety and the pH of the soil. Blooms on new wood.
Cultivars: Grandiflora (PeeGee), Tardiva, and Unique are older varieties. Limelight, Little Lime, and Vanilla Strawberry are recent cultivars.
Other ID features: These shrubs can take up to 6 hours of full sun, so you might find one thriving in a sunnier location than some other types. Because they bloom on new wood, you may find they have been pruned back hard. And if they’re thriving in northern climates, they’re probably H. paniculata.
4. Look at the Base of the Plant
H. arborescens, H. macrophylla, and H. serrata all have snowball-type flower heads, and the Bigleaf and Mountain types also have lacecap flower varieties. To tell these three apart, look at the growth habit. H. arborescens has many individual stems coming up from the ground. You may also see evidence of stems that have been cut back in previous years. H. arborescens blooms on new wood and is cut back to the ground every year.
Mountain and Bigleaf have many branches from one low-to-the-ground “trunk.” Because they bloom on old wood, they should not be heavily pruned.
Common names: Smooth hydrangea, snowball hydrangea, wild hydrangea, Annabelle. The cultivar “Annabelle” is named after the town of Anna, Illinois, where it was a pass-along plant among friends and neighbors for decades until it was “discovered” in the 1960s.
USDA hardiness zone: 3 to 9 (native to the eastern United States)
Size and shape: Loose, rounded shrub 3 to 4 feet tall and wide
Growth rate: Moderate to fast – established plants grow to mature height each season when cut down in late winter/early spring.
Leaves: More rounded than other types, with a smooth surface. Older leaves have petioles that are 1 inch long or longer.
Flowers: Fragrant, large, round “snowball” blooms, usually white, blooming on new wood at the ends of the stems. Flowers often start green, then turn white.
Cultivars: Annabelle, Invincibelle, Incrediball
Other ID features: Dried flowerheads persist through the winter.
5. The Last Two Varieties
So now you are left with H. macrophylla and H. serrata. These two are related; H. serrata may be a subspecies of H. macrophylla. They have both been used to create many cultivars, especially reblooming varieties.
Common names: Hortensia, French or Bigleaf Hydrangea
USDA hardiness zone: 6 to 9, marginally hardy to zone 5 (native to Japan)
Size and shape: rounded shrub, 3 to 6 feet tall and wide
Growth rate: Medium to fast
Leaves: Large, serrated green leaves with shorter petioles (less than 1 inch) that turn yellow in the fall. Some cultivars have a reddish fall color.
Flowers: Large lacecap or mophead; flowers are pink, purple, or blue depending on the pH of the soil. Blooms on old wood; flower buds can be killed by cold weather.
Cultivars: Nikko Blue, Blushing Bride, Charm
Other ID features: There are white-flowered cultivars, but they are not common.
Common name: Mountain hydrangea
USDA hardiness zones: 6 to 9, possibly to zone 5 with winter protection (native to Japan and Korea)
Size and shape: Rounded shrub 4 to 5 feet tall and wide
Growth rate: Medium, grows about 18 inches per year in ideal conditions
Leaves: Serrated, dull green to 6 inches long; reddish fall color
Flowers: Lacecaps that bloom pink, purple, or blue depending on the soil pH. Blooms on old wood; buds may freeze in cold weather.
Cultivars: Bluebird, Diadem, Preziosa
Other ID features: Related to H. macrophylla, but smaller flowers and narrower leaves give it a finer texture.
We hope this guide helped you identify your hydrangea. If you still aren’t sure what type it is, let it grow without pruning for a season. You should be able to identify it by the flowers. Make sure to check out our other articles on encouraging them to bloom and how to take care of them properly.