Smooth Hydrangea is a perennial grown for its white blooms, which open in spring and return year after year. It's hardy across USDA zones 3 through 9 and grows just as well in a container as in the ground. Its spring flowers are a moderate draw for honeybees and native bees.
Smooth Hydrangea — the short answer
Smooth Hydrangea: grown in zones 3–9, part sun, pH 5–7.5.
- USDA zones
- 3–9
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Soil pH
- 5–7.5
- Growable Ground Plant Database
- Sun
- Part Sun
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — each tile names its own row's source, because per-field provenance varies.
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Zone averages can't see the slope, soil, frost, and sun that decide whether smooth hydrangea actually takes — and those shift from one yard to the next. Enter your address and we'll score smooth hydrangea against your land's real conditions.
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What Smooth Hydrangea is
Smooth Hydrangea grows as a perennial and reaches around five feet at maturity. It blooms white in spring. It's also well suited to containers.
How to grow Smooth Hydrangea
Smooth Hydrangea grows in USDA zones 3 through 9. Smooth Hydrangea does best in part sun — at least 4 hours of direct sun a day — and soil from pH 5 to 7.5, on well-drained ground. It needs a growing season of at least 90 frost-free days and about 800 hours of winter chill, which is why climate matters as much as soil.
USDA Zones
3-9
USDA PHZM 2023
Soil pH
5 - 7.5
Growable Ground Plant Database
Sun
Part Sun
Growable Ground plant catalog
Drainage
well (dry spells)
Growable Ground plant catalog
Mature Height
5 ft
Growable Ground plant catalog
Chill Hours
800+
Winter hours below ~45°F it needs to fruit — too-mild winters can leave it bloom-shy.
Growable Ground plant catalog
Frost-Free Days
90+
The frost-free stretch it needs start to finish — short-season areas may need an indoor head start.
Growable Ground plant catalog
Start the season right
Plant smooth hydrangea in part sun with at least 4 hours of direct sun. It grows in the cool halves of the year, so sow it in spring or late summer rather than waiting for midsummer heat.
Match the soil
Smooth Hydrangea prefers pH 5 to 7.5 (Growable Ground Plant Database). A quick soil test from your local Extension lab tells you whether to add lime or sulfur to land in band.
Water steadily
Keep the root zone evenly moist through establishment. A 2–3 inch mulch layer holds moisture without waterlogging.
Harvest at its peak
Cut smooth hydrangea blooms in the cool of the morning, just as they open, for the longest display.
Where Smooth Hydrangea thrives
Smooth Hydrangea is hardy across USDA zones 3 through 9. Zone is only the starting point, though: the soil pH, drainage, and frost dates on your specific land decide how well it actually does.
A USDA zone is a 10°F band of average annual extreme winter minimum, so zones 3–9 spans average winter lows from -40°F to 30°F (USDA PHZM 2023). Across the 50 states and DC, that band covers 42 outright and splits 9 more down the middle — and which side of that line your land sits on changes the answer.
Zones 3–9·Where Smooth Hydrangea growsOpen map →
Where Smooth Hydrangea stands, state by state
Smooth Hydrangea is rated for zones 3–9 — a cold floor USDA puts at -40 to -30°F. Across the 50 states and DC, 42 sit fully inside that band, the line runs through 9 more, and 0 sit outside it — and inside every split state, the same line runs on at county grain.
Fully inside zones 3–9
42 states
3 of 42 shown
The line runs through
9 states
- Alaska · zones 1a-9a
- California · zones 4b-11a
- Nevada · zones 4a-10a
3 of 9 shown
Smooth Hydrangea’s band covers part of each of these states — which side of the line your county sits on changes the answer, and each state page draws it.
State zone extents: USDA Plant Hardiness Zone Map (PHZM) 2023. A zone is a 10°F band of average annual extreme minimum temperature, so a state that splits the band contains the boundary — its own page draws the county line, and a parcel report resolves which side your land sits on.
What grows around Smooth Hydrangea
Growing guides for smooth hydrangea
In rotation planning, smooth hydrangea counts as a Other — beds recover best when other crops don’t follow each other in the same spot year over year. (Growable Ground derivation — crop-rotation group from botanical family)
Good to know
One caution for pet owners — smooth hydrangea is toxic to dogs and cats and horses (moderate severity). Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)
Smooth Hydrangea offers moderate value to bees and other pollinators. (Source: Lady Bird Johnson Wildflower Center.)
Your land is one point inside Smooth Hydrangea's range
This page resolves to the species. Your state page draws the county line, and a report reads the parcel — the soil pH, drainage, sun, and frost dates on your exact ground, which no species average can see.
See if Smooth Hydrangea will thrive on your land
Zone averages are a start. Your exact soil pH, drainage, sun exposure, and frost dates shape whether smooth hydrangea actually takes — we score it against the real conditions at your address.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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How we know this about Smooth Hydrangea
The figures above are cited per row, not per site: the pH band names this plant’s own source column, the three temperature figures each carry their own, and days-to-maturity cites the publication that actually lists it. All of it comes from the Growable Ground Plant Database — a compilation over FAO ECOCROP, USDA PLANTS, and university Extension sources, published openly with per-field provenance.
Grounded inUSDA PLANTS Database•USDA PHZM•ASPCA
Frequently asked questions
Can I grow Smooth Hydrangea in my zone?
Smooth Hydrangea grows in USDA hardiness zones 3 through 9 (USDA PHZM 2023). Zone is one factor — soil pH, drainage, and frost dates on your specific parcel also shape whether it takes.
When should you plant Smooth Hydrangea?
Smooth Hydrangea is a cool-season crop, so it goes in during the cool halves of the year — early spring, and again in late summer for a fall planting — rather than at the height of summer heat. Your local frost dates set the exact window — a Growable Ground report reads them for your address.
How much sun does Smooth Hydrangea need?
Smooth Hydrangea does well in partial sun — around 4 hours of direct sun, and it takes some afternoon shade in stride. That flexibility makes it a good match for a bed the house or a nearby tree shades for part of the day. A Growable Ground report maps how the sun actually falls on your land, hour by hour, so you can set it where the light lines up.
What soil does Smooth Hydrangea need?
Smooth Hydrangea prefers soil pH 5 to 7.5, on well-drained ground (Growable Ground Plant Database). Your report scores your parcel's actual soil against that using USDA SSURGO data.
Does Smooth Hydrangea attract pollinators?
Yes — smooth hydrangea's flowers are a solid nectar source for honeybees and native bees. (Source: Lady Bird Johnson Wildflower Center.)
Is Smooth Hydrangea safe for pets?
Smooth Hydrangea is toxic to pets (dogs,cats,horses) with moderate severity. Keep it out of reach, and call ASPCA Animal Poison Control at (888) 426-4435 in an emergency. (Source: ASPCA.)