Rose of Sharon (Hibiscus syriacus) - purple flowers, illustrated plant card

Illustration

Rose of Sharon

Hibiscus syriacus

Also called althea and althaea

Rose of Sharon blooms from July through September.

Design a garden with this →Shop rose of sharon at Plant Addicts(paid link)

Bloom calendar

Bloom time

Jul–Sep

not yet checked

Hardiness

Zones 5–9

checked

Sun

Full sun

checked

Water

Moderate water

not yet checked

Mature size

8 ft × 6 ft

checked

Type

Shrub

house classification

Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.

Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–9. Expect it to reach about 8 ft tall and 6 ft wide at maturity, in roughly 4 years (not yet checked).

Verification

Core facts checked

What was checked

Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.

See the 9 sources it was checked against

When to plant Rose of Sharon

Plant Rose of Sharon in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 7, the middle of its hardy zones 5 to 9, spring means March to May and fall means September or October. Once settled, it blooms from July to September.

Month-by-month timing for your zone is on the planting calendar; if you garden near zone 7, the middle of this plant's hardy range, start with zone 7 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.

How big does Rose of Sharon get?

Illustration of Rose of Sharon drawn to scale beside an adult — About 8 ft tall and 6 ft wide at maturity: half again as tall as an adult.

See Rose of Sharon in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.

How far apart to plant Rose of Sharon

Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.

Space Rose of Sharon about 6 ft apart, center to center, so each plant has room to reach its full width.

Plant them

6 ft apart

Per 10 sq ft

one needs about 36 sq ft

4 by 8 ft bed

about 1

Add Rose of Sharon to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.

Where these facts come from

Rose of Sharon's height, spread, hardiness zones, sun and trait tags were checked against 9 published sources on July 30, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.

NC State ExtensionHibiscus syriacusheight, spread, hardiness zones, sun, years to mature size and trait tags
Proven WinnersRose of Sharon growing guideheight, spread, hardiness zones, sun, years to mature size and trait tags
depts.ttu.eduTexas Tech University Woody Plant Finder (Hibiscus syriacus)height, spread, hardiness zones, sun and trait tags
Missouri Botanical GardenHibiscus syriacusheight, spread, hardiness zones, sun and trait tags
The Morton ArboretumRose-of-Sharonhardiness zones, sun, years to mature size and trait tags
University of Florida IFASUF/IFAS Extension Nassau County fact sheet (Rose-of-Sharon)height, spread, sun and years to mature size
Clemson Home and Garden Information CenterHibiscusheight, spread and hardiness zones
Oregon State UniversityHibiscus syriacusheight, hardiness zones and sun
dendro.cnre.vt.eduVirginia Tech Dendrology Fact Sheet (Hibiscus syriacus)height

How the checking works, and what each standard covers, is on the verified plants page.

Comes in 12 varieties across 5 colors

Same plant, same care - pick the color you are growing.

Compare every variety in the Rose of Sharon group

Every figure is the variety's own page fact. Tap a name to open it.

Variety	Color	Blooms	Hardiness	Sun	Size (H × W)
Aphrodite	Pink	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Blue Bird	Blue	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Blue Chiffon	Blue	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Blushing Bride	Pink	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Diana	White	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Helene	White	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Lavender Chiffon	Purple	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Lucy	Red	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Minerva	Pink	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Purple Pillar	Purple	Jul–Sep	Zones 5–9	Full sun	10 ft × 2.5 ft
Red Heart	White	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
Rose ofthis page	Purple	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft
White Chiffon	White	Jul–Sep	Zones 5–9	Full sun	8 ft × 6 ft

Good to know about Rose of Sharon

Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.

Worth knowing

Native to south China and Taiwan, not Syria or the Mediterranean as the name 'syriacus' and 'Rose of Sharon' suggest. per NC State

Can outgrow its compact size

Sources split on size: a compact 5 to 8 ft shrub, a large 8 to 12 ft one, even 15 ft as a tree. Prune to keep it small. per Morton and NC State

Warm-end limit varies

Every source agrees it is cold-hardy to zone 5. The warm end splits: NC State allows zone 9, but Illinois, Virginia Tech and Morton stop at zone 8. per NC State and Illinois

Reseeds heavily; can be weedy

Fertile forms self-sow heavily, scattering volunteer seedlings and even escaping into wild areas; it is listed invasive in several states. Deadheading the seed capsules stops most of it. per NC State and UConn

Sterile cultivars avoid seedlings

Single-flowered triploids 'Diana', 'Helene', 'Aphrodite' and 'Minerva' set almost no seed yet keep the open flowers pollinators feed on, unlike fully double sterile forms. per Clemson and Virginia Tech

Blooms on new wood

It flowers on the current season's growth, so prune while dormant in late winter to early spring. Cutting back a third each year boosts flower size. per Illinois and UConn

Safe for pets

The ASPCA lists it non-toxic to dogs, cats and horses, and NC State agrees. A pet that gorges on it may still get a mild, brief stomach upset. per ASPCA and NC State

What pairs well with Rose of Sharon

Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.

Sea Thrift
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; low at 8 in, to carpet the ground beneath; evergreen, so the bed keeps its shape through winter.
Aster
Shares full sun and moderate water; overlaps, then carries the display into mid fall; its seed heads stand through winter, for structure and the birds; both offer pollinator forage.
Pansy
Takes full sun to part sun and moderate water; blooms in early spring, before this one opens; low at 8 in, to carpet the ground beneath; both offer pollinator forage, in different months.
Chives
Shares full sun and moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; low at 12 in, to carpet the ground beneath.
Tulip Tree
Shares full sun and moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; stands well above at 66 ft, a canopy to plant beneath.
Common Comfrey
Shares full sun and moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; lower at 2.5 ft, for the front of the border.
Hyacinth
Shares full sun and moderate water; blooms in early spring, before this one opens; low at 10 in, to carpet the ground beneath; both offer pollinator forage, in different months.
Ninebark
Shares full sun and moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; its white flowers settle the purple.