Smooth Hydrangea Shrub

Smooth Hydrangea: A Native Shrub With Big White Summer Blooms

Smooth hydrangea (Hydrangea arborescens) is a native deciduous shrub that grows 3 to 5 feet tall and wide and covers itself in rounded white flower clusters from June into September. Smooth hydrangea is hardy in USDA zones 3–9 and grows in part shade to sun. TN Nursery ships bare-root shrubs, Buy 1 Get 1 Free.

Smooth hydrangea is a member of the hydrangea family, Hydrangeaceae, and grows wild on wooded slopes, ravines and stream banks from New York and Illinois south to Florida and Louisiana, including the hollows and bluffs of Tennessee. Gardeners also know smooth hydrangea as wild hydrangea, sevenbark (for the peeling layers of bark on older stems) and smooth leaf hydrangea. The broad, toothed, heart-shaped leaves are soft green, and the flower heads open lime green, turn bright white and then age to soft green and tan. Popular garden selections such as 'Annabelle' and Snow Hill hydrangea ('Grandiflora') come from this same native species.

• Botanical name: Hydrangea arborescens, hydrangea family (Hydrangeaceae)
• Also called: wild hydrangea, sevenbark, smooth leaf hydrangea, Hydrangea arborescens
• Mature size: 3–5 feet tall and 3–5 feet wide, a rounded multi-stemmed shrub
• Flower: rounded white clusters 4–6 inches across, June through August, with fresh blooms into September
• Best uses: shade gardens, woodland edges, foundation plantings, mass plantings, cottage gardens and cut or dried flowers
• Wildlife value: summer nectar and pollen for native bees and butterflies; host plant for the hydrangea sphinx moth; seeds for songbirds
• What ships: bare-root shrubs in 1–2, 2–3 and 3–4 ft sizes, as Buy 1 Get 1 Free, Buy 3 Get 2 Free or 25-shrub wholesale bundles

What Is a Smooth Hydrangea?

A smooth hydrangea is a North American native hydrangea, Hydrangea arborescens, that blooms on new wood every summer and stays white regardless of soil pH. Smooth hydrangea is the most cold-hardy hydrangea commonly grown in gardens, hardy to zone 3.

Because smooth hydrangea forms flower buds on the current year's stems, the shrub blooms reliably every summer, even after a cold winter. The flowers stay crisp white in acidic, neutral or slightly alkaline soil, so there is no need to adjust soil pH the way gardeners do for bigleaf hydrangeas. The papery flower heads hold their shape into winter and add texture to the garden after the leaves drop.

Does Smooth Hydrangea Grow in Sun or Shade?

Smooth hydrangea grows best in part shade, with morning sun and afternoon shade, and it grows in full sun in the North when the soil stays evenly moist. Smooth hydrangea also blooms well in the bright, dappled shade under tall trees.

Smooth hydrangea prefers moist, well-drained soil rich in organic matter and adapts to loam, clay and rocky woodland soils. Water deeply once a week through the first summer. A 2- to 3-inch layer of shredded leaves or bark keeps the roots cool and moist and feeds the soil as the mulch breaks down. Once established, smooth hydrangea is a dependable, easy-care shrub for the shady side of the house.

When Should You Prune Smooth Hydrangea?

Prune smooth hydrangea in late winter or early spring, before new growth begins. Smooth hydrangea blooms on new wood, so pruning at that time never removes the coming summer's flowers.

Snipping off the first flush of faded blooms in July often encourages a second, smaller set of flowers in August and September.

What Is the Difference Between Smooth Hydrangea and Bigleaf Hydrangea?

Smooth hydrangea is a native shrub that blooms white on new wood and is hardy in zones 3–9, while bigleaf hydrangea (Hydrangea macrophylla) is an Asian shrub that blooms pink or blue on older stems and is hardy mainly in zones 5–9. Smooth hydrangea gives the most dependable summer bloom in cold climates.

Many gardeners grow both: smooth hydrangea for bright white mass plantings and woodland edges, and a blue hydrangea for color near a patio or entry.

How Do You Plant Bare-Root Smooth Hydrangea?

Plant bare-root smooth hydrangea while the shrub is dormant, from late fall through early spring, setting the crown at the same depth it grew in the nursery and spacing shrubs 3 to 5 feet apart.

At our Altamont, Tennessee nursery, TN Nursery digs smooth hydrangea shrubs while they are dormant and ships them bare root, with no soil around the roots. Each shrub arrives as a dormant, multi-stemmed plant in the size you choose.

1. Soak the roots in water for 1 to 2 hours.
2. Dig a hole twice as wide as the roots and as deep as the root system.
3. Set the shrub so the soil line on the stems matches the ground level.
4. Backfill with soil mixed with compost and firm gently.
5. Water deeply and mulch 2 to 3 inches deep, keeping mulch off the stems.

What Grows Well With Smooth Hydrangea?

Native shrubs, ferns and woodland ground covers grow well with smooth hydrangea. Arrowwood viburnum adds spring flowers and blue fall berries behind it, and winterberry holly brings red winter fruit. In front, Christmas fern and lady fern add fine texture, and wild ginger forms a low green carpet around the base. Explore more in our flowering shrubs and shrubs for shade collections.

Planting & Growing Information

Botanical Name: Hydrangea arborescens
Plant Family: Hydrangeaceae
Ships: Bare root, dormant; 1–2, 2–3 and 3–4 ft
Planting Zone: 3–9
Height at Maturity: 3–5 feet
Width at Maturity: 3–5 feet
Spacing: 3–5 feet
Sun or Shade: Part shade; full sun with steady moisture
Water Needs: Moderate to high; keep soil evenly moist
Soil: Moist, well-drained soil rich in organic matter; any pH
Bloom Season: June–August, with repeat blooms into September
Flower Color: White, opening lime green
Origin: Eastern United States
Care: Prune in late winter or early spring. Mulch each spring and water during dry summer weeks.
Plant Attributes: Native, blooms on new wood, cold hardy, shade tolerant, long-lasting cut and dried flowers, pollinator friendly

Smooth Hydrangea FAQ

How big does smooth hydrangea get?

Smooth hydrangea grows 3 to 5 feet tall and 3 to 5 feet wide, forming a rounded, multi-stemmed shrub.

When does smooth hydrangea bloom?

Smooth hydrangea blooms from June through August, and removing the first faded flowers often brings more blooms into September.

Does smooth hydrangea bloom every year?

Yes. Smooth hydrangea blooms every summer because the flowers form on new stems that grow each spring.

Is smooth hydrangea native?

Yes. Smooth hydrangea is native to the eastern United States, from New York and Illinois south to Florida and Louisiana.

Does smooth hydrangea change color with soil pH?

No. Smooth hydrangea flowers stay white in any soil pH, aging to soft green and tan in late summer.

What zones does smooth hydrangea grow in?

Smooth hydrangea grows in USDA hardiness zones 3 through 9.

Grown and Shipped by TN Nursery

TN Nursery has grown hardy native plants since 1959, more than 65 years of experience, and has supplied plants to major U.S. landmarks like the Washington Monument and Arlington National Cemetery. At our Altamont, Tennessee nursery, we grow and ship native shrubs like smooth hydrangea to gardens across the country. Each shrub is dug while dormant and packed bare root so the roots settle in quickly and the shrub blooms on its first new growth. Want to learn more first? Read Snow Hill Hydrangea Care Guide, When to Prune Hydrangeas and Caring for Hydrangeas on our garden blog.