Seedless (Sterile) Blooming Rose Of Sharon Shrubs

'Lavender Chiffon' althea

Rose of Sharon, aka shrub althea, (Hibiscus syriacus) is a woody hibiscus shrub that is hardy in temperate northern areas of the U.S. (USDA hardiness zones 5-9). This summer flowering shrub is exceptionally easy to grow. 

At one time,  it was a great pass-along shrub that fell out of favor. However, old fashioned varieties frequently reseeded around the garden. New cultivars strut variegated foliage, double flowers, and infertile (sterile) blooms that produce little or no seed. They are available in a wide range of flower colors including pink, purple, blue, white, and almost red. 

Blooms may be single, semi-double, and double and range in size from 2-5 inches across. They grow in average to good garden soils with moderate drainage. For maximum flowering, site plants where they receive 6 or more hours of direct sun and feed annually with a slow-release fertilizer such as Osmocote™ or Nutricote™. Blooms attract numerous bees and butterflies. Japanese beetles may damage the flowers for a few weeks in early summer, but shrubs rapidly recover.

After their first year, Rose of Sharons are highly drought tolerant. Shrubs respond well to annual pruning and to severe “rejuvenating” by pruning to a few inches above the ground.

Some gardeners opt to grow them as perennials by cutting the plant back every year or two. In late spring the “shortened” plant(s) emerge as multi-stems, grow a 2-3 feet tall, and flower.

Alternative technique: thin out emerging growth to 1, 3 or 5 main shoots to train into a small patio tree.

Utilize Rose of Sharon as a specimen shrub or small tree, as a shrub border, or set into a large container. Best of the sterile forms of Rose of Sharon (althea):

Chiffon® series feature anemone-like double blooms for low seed set and long-blooming; color choices: Lavender (purple), Blue, and White; 8-12 feet x 6-10 feet wide.

Sugar Tip® - pure pink double blooms (no seed) and variegated semi-double creamy-white blooms/ bluish-green foliage; 8-12 feet x 6-8 feet.

Purple Pillar® - slender columnar growth habit (16 feet tall x 3 feet wide), 4-inch vibrant purple single to semi-double flowers with red centers; ideal fit for small urban gardens.