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Mountain hydrangea

Mountain hydrangea

Hydrangea serrata
Mountain hydrangea is a compact, deciduous flowering shrub native to the mountainous regions of Japan and Korea, where it grows in cool, moist, partly shaded conditions - and that cool mountain origin is the honest catch. Hardy through USDA Zone 6 when dormant, the plant breaks dormancy early and its new spring growth is reliably vulnerable to late frosts; a single late freeze in April can destroy an entire season's bloom on wood that would otherwise flower in midsummer. It is smaller and more refined than bigleaf hydrangea, with serrated leaves and distinctive lacecap flowerheads in blue or pink depending on soil pH, making it a graceful focal point for partly shaded borders where consistent moisture can be maintained.
Climate fit: narrow (30/100)
Focal point
Border
Structure
Container
Pollinator
Light
Part sun / Part shade
Water
Consistent moisture
Mature size
2-4 ft tall · 4 ft apart
Hardy in zones
6a-9b
cold to frosty winters
Native in Illinois
No

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The showy sterile ray florets of the lacecap surround a central cluster of small fertile florets that produce nectar and attract bees and other insects.

Cold hardiness

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.
Now
Zone 6b
Plotwright
USDA Zone 6b
-5°F to 0°F
Well-suited
Zone 7a
Plotwright
0°F to 5°F
Well-suited
In plain terms: This location has cold winters. Its winters are projected to keep warming through 2050.
Well-suited today and still thriving in 2050.

Heat tolerance

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.
Loading AHS heat-zone data for this location...

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Browse lateral options with similar roles, light needs, size, or native-range overlap; these are not filtered for a better climate fit.
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Educator packet

Plant packet
Mountain hydrangea educator packet
Mountain hydrangea is a compact, deciduous flowering shrub native to the mountainous regions of Japan and Korea, where it grows in cool, moist, partly shaded conditions - and that cool mountain origin is the honest catch. Hardy through USDA Zone 6 when dormant, the plant breaks dormancy early and its new spring growth is reliably vulnerable to late frosts; a single late freeze in April can destroy an entire season's bloom on wood that would otherwise flower in midsummer. It is smaller and more refined than bigleaf hydrangea, with serrated leaves and distinctive lacecap flowerheads in blue or pink depending on soil pH, making it a graceful focal point for partly shaded borders where consistent moisture can be maintained.
Scientific name
Hydrangea serrata
Plant type
shrub
Hardiness
6a-9b
Light
part-sun, part-shade
Moisture
consistent
Spacing
48 inches
Classroom prompts
- Which plant traits are observations, and which are care recommendations?
- How would this plant fit change if the garden location moved warmer, colder, wetter, or drier?
- Which source-backed facts would you cite in a lesson handout?
Use the Sources & citations section below for page citation styles and the field-level source list.

Sources & citations

Cite this page
For lesson plans, articles, or research that uses this page. Use the source cards below to explore the references that informed this record.
Plotwright. (2026, May 17). Mountain hydrangea (Hydrangea serrata). Retrieved 2026, August 20, from https://plotwright.com/plants/hydrangea-serrata
Sources used for this record
This record is compiled from the sources below.
RHS Find a Plant
Botanical research database
GBIF
Botanical research database
Wikipedia (ecoregion articles)
Botanical research database
Wikimedia Commons
Photo · CC BY 2.0