This fast-growing, native hydrangea has extreme cold tolerance.

The smooth hydrangea (Hydrangea arborescens) is a deciduous flowering shrub native to the eastern United States, where it grows wild on stream banks and wooded slopes.

However, you won’t often see the true native smooth hydrangea gracing gardens and landscapes, and there's a reason for that.

While Hydrangea arborescens is beloved in the wild for its delicate, flat-topped clusters of greenish-white blooms, it has floppy stems and an open growth habit that make it a bit unruly in the garden, especially after a heavy rain.

What you will find at nurseries are cultivated varieties bred to solve the flopping problem.

These popular cultivars typically sport large, globe-shaped flower clusters in shades of white or pink, along with sturdier stems that hold up under the weight of their blooms.

But here’s the catch: not all cultivars are created equal when it comes to supporting wildlife.

Many of these garden-friendly varieties don’t produce nectar or pollen for bees and other pollinators.

So, if you're planting with biodiversity in mind, look for cultivars that support insect life.. You'll find a list of pollinator-friendly options below.

Smooth hydrangeas are incredibly cold-hardy and thrive in USDA zones 3 through 8. Not sure what zone you're in? You can find it using the USDA Plant Hardiness Zone Map.

They prefer full sun to part shade and rich, moist, well-draining soil. To promote the development of strong stems, site this shrub where it will receive at least 3 hours of direct sunlight per day.

Smooth hydrangeas tolerate full sun with adequate moisture, but in hotter climates, afternoon shade is recommended.

And unfortunately, they are not deer-resistant. Deer will eat hydrangea flower buds and leaves, especially the tender young growth.

If you would like to grow a flowering shrub that deer tend to leave alone, try a Ruby Spice summersweet shrub.

Keep reading to learn how to grow smooth hydrangea, explore landscaping ideas, discover standout cultivars, and see how it compares to the popular bigleaf hydrangea.

4 large round greenish white smooth hydrangea flowers and dark green leaves — Incrediball® Smooth Hydrangea. Image courtesy of Proven Winners Color Choice Flowering Shrubs, provenwinners.com.

How to Plant and Grow the Smooth Hydrangea

Planting: The best time of year to plant a smooth hydrangea is in the spring or fall, giving the roots time to establish before the onset of extreme hot or cold weather. Water deeply immediately after planting. Read “How to Water Your Plants” for watering tips and strategies.

Location: Choose a location with well-draining soil rich in organic matter - smooth hydrangeas prefer soil that retains moisture but is not soggy. Select a spot with at least 3 hours of direct sunlight, and protection from the intense afternoon sun in zones 6 and higher.
Soil: To improve drainage and soil fertility, amend the soil with organic matter like compost, shredded leaves, or Leaf-gro®.
Mulch: Apply a layer of organic mulch around the base of the plant to retain soil moisture and suppress weeds. Make sure the mulch does not touch the base of the plant.
Watering: Smooth hydrangeas love moisture, so aim to keep the soil consistently moist but not waterlogged, especially during periods of drought. Are you in a drought? Check the U.S. Drought Monitor map.
Pruning: Smooth hydrangeas flower on new wood and can pruned in late winter or early spring. Plants may be hard pruned back to 12 inches, and suckers can be clipped off below the soil line.

What is an ‘Annabelle’ Hydrangea?

The Annabelle hydrangea (Hydrangea arborescens ‘Annabelle’) is a popular cultivated variety of Hydrangea arborescens. It is not synonymous with the straight species.

Instead, the Annabelle hydrangea represents a specific genetic variation of Hydrangea arborescens, with its own unique characteristics.

Many people consider the Annabelle hydrangea to be a nativar - a cultivated variety of a native plant species, chosen for having particular genetic traits.

‘Annabelle’ was discovered by Harriet Kirkpatrick in 1910, in Southern Illinois. Harriet noticed a hydrangea with unusually large, rounded blooms growing wild alongside a horseback riding trail.

She subsequently dug up this unusual shrub and transplanted it into her own garden.

After intense admiration from friends and neighbors, she propagated the plant and shared the offspring locally.

Through word-of-mouth, Harriet’s discovery spread regionally and the shrub became a popular smooth hydrangea variety in Illinois.

In the early 1960s, Dr. Joseph McDaniel of the University of Illinois collected and propagated samples of this shrub discovered by Harriet, leading to the start of its commercial production in 1962 under the name ‘Annabelle’.

The Annabelle cultivar and the straight species of smooth hydrangea share many similarities, yet also have distinct differences:

Both grow 3 -5 feet tall and wide and have an upright suckering habit.
Both prefer partial shade and moist, well-draining soil.
Both have flower heads comprised of clusters of smaller white florets.
Both have stems that tend to flop over from the weight of their flower heads, especially after a heavy rain.
The size and shape of their flower heads is different - Annabelle has large, rounded, ball-shaped flower heads growing up to 12 inches in diameter; the straight species has flattened flower heads that grow 6 - 8 inches wide.
Their ability to sustain pollinating insects differs - Annabelle has mostly sterile florets and brings no value to pollinators, while the straight species has mostly fertile florets and is rich in nectar and pollen, which attracts and supports pollinators.

annabelle hydrangea covered in white flowers growing in a landscape — The Annabelle hydrangea. Image courtesy of Bailey Nurseries.

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Smooth Hydrangea vs. Bigleaf Hydrangea

The smooth hydrangea (Hydrangea arborescens) and the bigleaf hydrangea (Hydrangea macrophylla) are two distinct species of plants belonging to the Hydrangeaceae family, with several key differences:

Native Range: Smooth hydrangeas are native to the eastern United States, while bigleaf hydrangeas originate from Japan and Korea.
Hardiness: Smooth hydrangeas can tolerate colder garden temperatures, growing happily in zones 3 - 8. Bigleaf hydrangeas are hardy in zones 6 - 9, and can also grow in zone 5 when winter protection is provided.
Leaves: Smooth hydrangeas have heart-shaped, slightly rounded, matte green leaves; bigleaf hydrangeas have large, oblong, fleshy leaves that are glossier in appearance.
Flower Color: Smooth hydrangeas have white, green or pink flowers regardless of the soil pH. The flower color of the bigleaf hydrangea is influenced by soil pH, with acidic soils producing blue flowers and alkaline soils producing pink flowers.

white smooth hydrangea flowers compared to blue bigleaf hydrangea flowers

Smooth Hydrangea Pruning

Pruning a smooth hydrangea is simple and essential for promoting healthy growth and abundant blooms.

This shrub blooms on new wood, meaning it produces flowers on the current season’s growth, so pruning is best done in late winter or early spring before new growth begins.

Start by removing any dead, damaged, or weak stems to improve air circulation and plant health.

For a fuller, bushier appearance, cut back the stems to about 12-18 inches from the ground, leaving strong, healthy buds intact.

Regular pruning not only keeps your hydrangea bush tidy but also encourages larger, more vibrant flowers throughout the growing season.

Do Smooth Hydrangeas Like Sun or Shade?

Smooth hydrangeas thrive in full sun to part shade, requiring at least 3 hours of direct sunlight per day to ensure strong stems and abundant flowering.

They can tolerate full sun, as long as adequate moisture is provided, and prefer protection from the intense rays of the hot afternoon sun.

In hot climates, providing them with morning sun and afternoon shade can help prevent their flowers and leaves from wilting and scorching.

In cooler regions, they may tolerate more sun, but protection from harsh afternoon sunlight is still recommended.

Landscaping Ideas for the Smooth Hydrangea

Mixed Foundation Planting: Plant smooth hydrangeas along the foundation of your home. Combine with a mix of evergreen and deciduous shrubs, creating four seasons of interest and enhancing the curb appeal of your home.
Native Garden: Plant the straight species of Hydrangea arborescens in a native garden, alongside oakleaf hydrangeas, woodland phlox, summersweet clethra, and other native plants.
Mixed Borders: Create a mixed border planting by combining the smooth hydrangea with small trees, shrubs, grasses and perennials.
Mass Planting: Plant smooth hydrangeas in large groupings to provide maximum visual impact. This approach works well in large garden beds and along pathways or fences.
Pollinator Garden or Bee Garden: Plant fertile, pollinator-favorite lacecap cultivars like ‘Haas’ Halo’ and ‘Pinky Pollen Ring’™ in the partially shaded areas of a pollinator garden.
Woodland Gardens: The partial shade underneath the canopy of tall trees is an ideal spot for the smooth hydrangea. Combine with other partial-shade loving plants like Japanese camellias, Japanese andromeda, azaleas, and rhododendrons.
Accent Planting: Use smooth hydrangeas as a focal point in the landscape. Plant strategically to draw attention to specific areas of the garden like entryways, water features, pathways, or seating areas.
Vintage Cottage Garden: For a charming, informal look, plant smooth hydrangeas alongside old-fashioned cottage garden favorites like foxgloves, garden phlox, hollyhocks, catmint, hibiscus, and roses.
Edging: Dwarf cultivars like Invincibelle Mini Mauvette® and Invicibelle Wee White® make great edging plants along walkways, sidewalks, and driveways.

smooth hydrangea with pink flowers and dark green leaves — **Invincibelle® Ruby Hydrangea.** *Photo courtesy of Proven Winners, provenwinners.com.*

Popular Smooth Hydrangea Cultivars

🐝 = cultivar that attracts pollinators

Annabelle (Hydrangea arborescens ‘Annabelle’): This popular variety has large, round flower heads growing up to 12 inches wide. Mature size is 3 - 5 feet high and wide. Stems are prone to flop, especially after a heavy rain.
Bounty 🐝 (Hydrangea arborescens ‘Bounty’): White flowers are similar to Annabelle, but with sturdier, more upright stems that resist flopping. Grows 5 feet tall and 8 feet wide.
Eco Pink Puff 🐝 (Hydrangea arborescens ‘Eco Pink Puff’): A pink-flowering shrub with small leaves. Grows 4-5 feet tall and 3-4 feet wide.
FlowerFull® 🐝 (Hydrangea arborescens ‘Bagful’): Improved disease resistance and flowers more heavily than other varieties, with bold white flowers held atop sturdy white stems. Grows 3-4 feet high and 4-5 feet wide.
Haas Halo 🐝 (Hydrangea arborescens ‘Haas’ Halo’): The fertile white lacecap flowers of this cultivar were given top ratings as a pollinator favorite in the Mount Cuba Center’s trial of Wild Hydrangeas for the Mid-Atlantic Region. Not widely available, but worth seeking out for those interested in supporting wildlife.
Incrediball® (Hydrangea arborescens ‘Abetwo’): An offspring of ‘Annabelle’, with large white flowers and stronger stems that resist flopping. Grows 5-8 feet tall and wide.
Incrediball® Blush 🐝 (Hydrangea arborescens ‘NCHA4’): Large pink fertile flowers cover a compact, 4-5 foot tall and wide shrub. Does best in full sun.
Invincibelle Limetta® (Hydrangea arborescens 'NCHA8'): Soft green flowers darken as the summer progresses. Grows 3-4 feet tall and wide.
Invincibelle Mini Mauvette® (Hydrangea arborescens ‘NCHA7’): A dwarf cultivar with deep mauve pink flowers atop sturdy, flop-resistant stems. Grows 2.5-3 feet tall and wide.
Invincibelle® Ruby (Hydrangea arborescens 'NCHA3'): Two-toned ruby red and pink flowers top darker green foliage. Grows 3-4 feet tall and 2-3 feet wide.
Invincibelle® Spirit II 🐝 (Hydrangea arborescens 'NCHA3'): Dark pink mophead flowers and a robust habit. Grows 3-4 feet tall and wide.
Invincibelle Sublime™ (Hydrangea arborescens 'SMNHRL'): Green mophead flowers on a 3-5 foot tall and wide shrub.
Invincibelle Wee White® (Hydrangea arborescens 'NCHA5'): A dwarf shrub, growing only 12-30 inches tall and wide. Large white flowers top strong stems.
Lime Rickey® (Hydrangea arborescens 'SMNHALR'): Flat, disc-shaped flowers change color during the season, from soft green to a darker green accented with pink pollen. A larger shrub, growing up to 6 feet tall and 8 feet wide.
Pinky Pollen RIng™ 🐝 (Hydrangea arborescens 'SMHALP'): This pollinator favorite has pastel pink lacecap flowers. Grows 4-5 feet tall and wide.
White Dome® 🐝 (Hydrangea arborescens ‘Dardom’): A large, upright, freely branching variety with lacy white blooms. Grows 4-6 feet high and wide.