Rose-of-Sharon, Shrub Althea (Hibiscus syriacus)

Summary:

Foliage: Deciduous broadleaf Height: 10 feet

Spread: 6 feet Shape: Upright

Rose-of-Sharon is a large shrub with showy, relatively large single or double flowers that bloom in summer. Flower colors include white, red, purple, violet, and blue.

Plant Needs:

Zone: 5 to 8

Light: Partial shade to full sun Moisture: Moist to dry

Soil Type: Sandy, loam, or clay pH Range: 3.7 to 7.3

Functions:

Suggested uses for this plant include border and mass plantings.

Planting Notes:

Transplants readily.

Tolerates wide range of soil pH. Salt tolerant.

Care:

Blooms occur on current year's growth, so prune in early spring before new growth starts. Remove one-third of the wood, including the oldest branches and any weak growth, at ground level, annually.

Problems:

Aphids are a problem on new growth. Susceptible to spider mites in hot, dry locations.

Other problems include leaf spots, blights, Japanese beetle, and white fly.

Will self sow and produce populations of seedlings in the vicinity of the parent plant(s).

Alternatives:

Consult local garden centers, historic or public gardens and arboreta, regarding cultivars and related species that grow well in your area.

There are numerous cultivars of H. syriacus in the trade. Cultivars of Hibiscus syriacus: `Blue Bird' has blue flowers.

`Diana' has white flowers that do not produce viable seed. `Helene' has white flowers with a reddish-purple base.

Comments:

This is a large shrub which flowers in late summer when few other shrubs are in bloom. Single or double flowers range in color from white to red to blue to all colors in between. Unless older portions of the plant are pruned regularly, the flowers will decrease in size.

This material was developed by Carol Ness as part of the Interactive Design and Development Project funded by the Kellogg Foundation.