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

checked

Hardiness

Zones 5–9

checked

Sun

Full sun

checked

Water

Moderate water

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 (a house reading).

Pets

Not yet checked for pets.

Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.

No toxicity note is on file for Rose of Sharon. That is not a clearance: check its safety for people and pets before planting.

Verification

Planting record checked

What was checked

Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. 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 15 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, water, bloom months and color and trait tags were checked against 15 published sources on October 29, 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, water, bloom months and color, years to mature size and trait tags
Missouri Botanical Gardenheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
Chicago Botanic Gardenheight, spread, sun, water, bloom months and color 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
Iowa State University Extensionspread, hardiness zones, sun and bloom months and color
Missouri Botanical GardenHibiscus syriacusheight, spread, hardiness zones, sun and trait tags
pubs.ext.vt.eduVirginia Cooperative Extensionheight, spread, hardiness zones, sun and water
The Morton ArboretumRose-of-Sharonhardiness zones, sun, water, years to mature size and trait tags
sunshinegrowersnursery.comSunshine Grower Nurseryheight, spread, hardiness zones and water
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
RHSRoyal Horticultural Societyheight, sun and water
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 13 varieties across 5 colors

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

Every plant in the group blooms from July through September.

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 5–8	Full sun	8 ft × 6 ft
Azurri Blue Satin	Blue	Jul–Sep	Zones 5–9	Full sun	10 ft × 5.5 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 5–8	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

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.
Decadence Vanilla Cream False Indigo
Shares full sun and moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; its seed heads stand through winter, for structure and the birds.
Yaupon Holly
Shares full sun and moderate water; blooms in mid spring, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Kinnikinnick
Shares full sun and moderate water; blooms in mid spring, before this one opens; low at 8 in, to carpet the ground beneath; both offer pollinator forage, in different months.
Prairie Junegrass
Shares full sun and low to moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; evergreen, so the bed keeps its shape through winter.
Carnival Scotch Heather
Shares full sun and moderate water; low at 8 in, to carpet the ground beneath; opens in early summer and overlaps into this one's season; evergreen, so the bed keeps its shape through winter.
Candytuft
Shares full sun and low to moderate water; blooms in mid spring, before this one opens; low at 10 in, to carpet the ground beneath; both offer pollinator forage, in different months.
Buffalograss
Shares full sun and low to moderate water; low at 8 in, to carpet the ground beneath; opens in early summer and overlaps into this one's season; its seed heads stand through winter, for structure and the birds.