Hibiscus syriacus

Rose-of-sharon, Shrub Althea

Malvaceae

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Habitat

  • native to China and India
  • hardy to zone 5
  • Special Note: This species has demonstrated an invasive tendency in Connecticut, meaning it may escape from cultivation and naturalize in minimally managed areas. For more information, .

Habit and Form

  • a deciduous, flowering shrub
  • 8' to 10' tall
  • 6' to 8' wide
  • upright, spreading branching
  • develops a vase-shaped outline
  • often leggy at the base
  • multi-stemmed with lots of vertical branches

Summer Foliage

  • alternate, simple, deciduous leaves
  • leaves 3-lobed
  • margins coarsely toothed
  • 2" to 4" long
  • medium to dark green
  • leaf surface glabrous sometimes shiny
  • late to leaf out in spring

Autumn Foliage

  • yellow-green
  • leave hold late
  • overall poor effect

Flowers

  • large, showy blossoms in July, August, and September
  • white, pink, magenta, violet, blue, and combinations of these
  • 5-petaled
  • 2" to 4" across
  • single or double
  • flowers are solitary
  • produced on current season's growth

Fruit

  • a brown capsule
  • 0.75" long
  • persists through the winter
  • 5-valved

Bark

  • light gray

Culture

  • full sun is best, but tolerant of partial shade
  • soils are not critical
  • easily transplanted
  • annual pruning back will result in increases shoot vigor and larger flowers
  • likes hot weather
  • may need to remove winter killed stems

Landscape Use

  • shrub border
  • screen
  • groupings and mass plantings
  • useful for late season bloom
  • do not use as a specimen plant
  • standard forms may be used as small trees

Liabilities

  • does not have multi-season ornamental appeal
  • winter injury and twig dieback
  • late to leaf out in spring
  • leaf spot, cankers, rust, aphids, spider mites

ID Features

  • 3-lobed leaves
  • late summer large flowers
  • distinctive vase-shaped habit
  • persistent 5-valved capsules
  • indistinct buds
  • shelf-like projections mark the position of previous flowers and fruit
  • thread-like stipules are persistent

Propagation

  • by cuttings
  • by seed

Cultivars/Varieties

Dozens of forms are available, but the following listing encompasses cultivars that indicate the range of types offered.

'Aphrodite' - This U.S. National Arboretum introduction features dark pink flowers exhibiting a dark red eyespot. The foliage is heavily textured. As this plant is a triploid, it should not produce as many seedlings. Some observations indicate ample seed production.

'Ardens', 'Blushing Bride' and 'Peoniflora' - These cultivars are just a few of the many forms sold at nurseries with double blooms of a pink or rose hue.

'Blue Bird' (also listed as 'Bluebird') - A form with single flowers that are a blue with a reddish base, this old form is still popular in the trade.

'Diana' - This triploid U.S. National Arboretum introduction is one of the best white-flowered forms. The blooms are large and lack a central blotch. They remain open at night and are produced over a long period due to little or no seed production. This plant appears to be less vigorous than other forms.

'Helene' - A triploid form producing white flowers that are maroon at the base, this U.S. National Arboretum introduction flowers heaviliy and sets little fruit.

'Minerva' - A heavy-blooming cultivar with lavender flowers overcast with some pink, this plant remains smaller and more shrubby (to 9' tall). The flowers have a red eye and the foliage is higher quality than the species. A U.S. National Arboretum introduction reportedly performing well into USDA zone 5.

'Pink Giant' - This form bears large, 5" wide pink blooms with a deep red central blotch. It grows 8' tall and wide.

'Purpureus Variegatus' and 'Meehanii' - These are two of the more common variegated forms, featuring leaves variously edged or mottled with white, yellow, and gray. The flowers are of secondary interest on these plants.

'Tri-color' - This is a very unusual cultivar with double flowers colored pink, red and purple on one plant.

© Copyright Mark H. Brand, 1997-2015.

The digital materials (images and text) available from the UConn Plant Database are protected by copyright. Public use via the Internet for non-profit and educational purposes is permitted. Use of the materials for profit is prohibited.

Citation and Acknowledgements: University of Connecticut Plant Database, http://hort.uconn.edu/plants, Mark H. Brand, Department of Plant Science and Landscape Architecture, Storrs, CT 06269-4067 USA.