Rose of Sharon

Hibiscus syriacus

Also called althea and althaea

Rose of Sharon blooms from July through September.

Bloom calendar

Bloom time

Jul–Sep

Hardiness

Zones 5–9

Sun

Full sun

Water

Moderate water

Mature size

8.2 ft × 5.9 ft

Type

Shrub

Verification

Core facts checked

Mature size, 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.

Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–9. Expect it to reach about 8.2 ft tall and 5.9 ft wide at maturity, in roughly 4 years.

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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. For the middle of its hardy zones 5 to 9 range, 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: for the middle of its range, start with zone 7 in March.

Comes in 12 varieties across 5 colors

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

Good to know about Rose of Sharon

Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.

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.
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.
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.
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; evergreen, so the bed keeps its shape through winter.
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.
Sage
Shares full sun and low to moderate water; blooms in late spring, before this one opens; both offer pollinator forage, in different months; lower at 1.6 ft, for the front of the border.