Spiraea tomentosa aka Steeplebush

Spiraea tomentosa, called steeplebush or hardhack, belongs to the rose family. It grows wild in eastern Canada and the eastern United States. Its range reaches south to Georgia and Louisiana. It grows in wet meadows, marshes, fields, and beside lakes. This shrub sheds its leaves each year. Several upright stems rise from its woody root system. Root suckers spread outward and can form dense patches. Garden plants reach about 2–5 feet (0.6–1.5 m) tall. Their spread reaches about 3–5 feet (0.9–1.5 m).

Young brown stems have a thick coat of soft hairs. Older stems lose these hairs and become woody. Simple leaves grow in an alternate pattern along the stems. They have an oval shape and coarse teeth along their edges. Leaves reach about 0.25 feet (0.08 m) long. Their upper faces are green, while pale hairs coat the undersides. The leaves feel leathery and lack strong fall color. Some stems die back to ground level during winter.

Pink to rose-purple flowers open from July through September. White flowers occur less often. Dense, narrow panicles rise from the ends of stems. These reach about 0.33–0.67 feet (0.10–0.20 m) long. Each small flower has five petals and many projecting stamens. Flowers open from the cluster's top downward, then turn brown. They have no clear scent. Butterflies visit the flowers. The leaves feed larvae of the New England buck moth. Each flower forms five small brown follicles. These ripen in September and October, then split to release slender seeds.

Give steeplebush moist soil and full sun for the best bloom. It also grows in light shade. North Carolina Extension favors acidic soil, including moist to wet sites. RHS lists a wider pH range and calls for good drainage. Both sources allow several soil types, including clay, loam, and sand. The shrub suits USDA zones 3–8 and carries the RHS rating H6. It needs little routine care. It blooms on new stems, so prune in late winter or early spring. Removing spent flower heads can encourage more bloom. Divide plants in late autumn or early spring.

Use this shrub beside ponds, in damp spots, or along paths. Groups suit borders, informal gardens, and wildlife plantings. Deer may browse it, but its bitter leaves discourage feeding. Serious pest and disease trouble is uncommon. Possible pests include aphids, scale, leafrollers, and other caterpillars. Leaf spot, fire blight, powdery mildew, and honey fungus may occur. Plants For A Future lists no known food uses or hazards. That does not establish that every part is safe to eat. It records past medicinal use of flowers, leaves, and roots. Those records do not establish treatment safety or effectiveness.