Smooth Hydrangea is a perennial grown for its white blooms, which open in spring and return year after year. Notably, it grows just as well in a container as in the ground. Its spring flowers are a moderate draw for honeybees and native bees.
Zones
Data not available
pH Range
5-7.5
Sun
Part Sun
Days to Maturity
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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 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
Data not available
USDA PHZM 2023
Soil pH
5 - 7.5
USDA PLANTS Database
Sun
Part Sun
plant_species_v5.csv
Drainage
well (dry spells)
plant_species_v5.csv
Mature Height
5 ft
plant_species_v5.csv
Chill Hours
800+
plant_species_v5.csv
Frost-Free Days
90+
plant_species_v5.csv
Start the season right
Plant smooth hydrangea in part sun with at least 4 hours of direct sun, once the soil has warmed and frost risk has passed.
Match the soil
Smooth Hydrangea prefers pH 5 to 7.5 (USDA PLANTS 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.
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: Xerces Society, Pollinator Partnership.)
Where Smooth Hydrangea thrives
Whether smooth hydrangea thrives on a given site comes down to its soil pH, drainage, sun, and frost dates — the conditions that vary parcel to parcel.
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.
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Frequently Asked Questions
Can I grow Smooth Hydrangea in my zone?
Zone data for smooth hydrangea is being finalized. A Growable Ground report checks your parcel's full suitability against federal soil, climate, and zone data.
When should you plant Smooth Hydrangea?
Most growers plant smooth hydrangea after the last spring frost, once the soil has warmed, leaving enough of the season for its 90-day frost-free need. 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 (USDA PLANTS 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 (Xerces Society, Pollinator Partnership).
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.