The ‘Double Purple’ Rose of Sharon (Hibiscus syriacus ‘Double Purple’) is a popular deciduous shrub known for its vibrant, reliable floral display. It consistently produces abundant blooms in late summer and fall, extending color when other plants fade. Its hardiness and adaptability allow it to thrive in various landscapes with simple care.
Characteristics of ‘Double Purple’ Rose of Sharon
The ‘Double Purple’ Rose of Sharon is admired for its distinctive double flowers, which are a rich purple hue. These blooms, often described as frilly, can reach 2 to 3 inches in diameter and feature multiple layers of petals, distinguishing them from more common single-petal varieties. They flower from midsummer into autumn, providing prolonged color.
This shrub exhibits an upright, vase-shaped growth habit, typically developing into a multi-stemmed plant. Mature plants typically reach 8 to 12 feet tall and 6 to 10 feet wide, though some variations exist. As a deciduous shrub, its leaves turn green with no significant fall color before dropping in late autumn, and new foliage emerges late in spring. It is hardy in USDA Zones 5 through 9, withstanding winter temperatures as low as -20°F.
Planting and Site Selection
Selecting an appropriate planting location is important for the successful establishment and long-term health of ‘Double Purple’ Rose of Sharon. This shrub thrives in full sun (at least six to eight hours of direct sunlight daily) for optimal flowering. Partial shade is tolerated, but too much can reduce blooms and increase fungal issues.
The ‘Double Purple’ Rose of Sharon adapts to a variety of soil conditions, though it prefers well-draining soil that is rich in nutrients. It tolerates a wide pH range (slightly acidic to neutral) and grows in loamy, sandy, or clay soils. Planting is best in spring after the last frost, or early fall (especially in southern climates), allowing root establishment before extreme temperatures.
Dig a hole twice as wide as the root ball and just as deep. Ensure the top of the root ball is level with or slightly above the surrounding soil. Backfill, gently tamping to remove air pockets, and water thoroughly. Space multiple shrubs 6 to 10 feet apart, depending on desired mature size.
Ongoing Care for ‘Double Purple’
Once established, ‘Double Purple’ Rose of Sharon is low-maintenance, tolerating heat, humidity, and drought. Young plants need regular watering for root establishment; mature shrubs require supplemental watering only during prolonged dry periods. Aim for about one inch of water per week (irrigation and rainfall combined). Yellowing leaves or dropped buds can indicate either overwatering or underwatering, so observing the plant and checking soil moisture is important.
Fertilizing is generally not necessary for established shrubs unless soil is poor. If desired, apply a slow-release granular fertilizer for shrubs and trees in early spring, following product instructions. Alternatively, a 1-2 inch layer of compost around the base in spring provides organic nutrients.
Mulching with shredded bark helps retain soil moisture, suppress weeds, and regulate soil temperature. While generally resistant, Rose of Sharon can encounter pests like aphids and diseases such as leaf spot or powdery mildew. Proper air circulation from good spacing and pruning helps prevent fungal issues. Aphids can be managed with a strong jet of water or insecticidal soap.
Pruning for Optimal Blooms
Pruning the ‘Double Purple’ Rose of Sharon is a beneficial practice for maintaining its shape, controlling its size, and promoting abundant, larger blooms. Since it flowers on new wood, prune in late winter or early spring before new growth and buds emerge. This timing directs energy into new, flower-bearing shoots.
Maintenance pruning involves removing dead, diseased, or damaged branches at any time. Also remove crossing or inward-growing branches to improve air circulation. To control size and shape, cut branches back to a node, removing about one-third of the plant’s overall size annually. For older, overgrown plants, rejuvenation pruning involves cutting older, taller branches down by two-thirds in late autumn or winter, though this may reduce blooms the following year. Consistent annual pruning prevents an untidy appearance and encourages continuous vibrant flowers.