Spiraea tomentosa
steeplebush
Overview
Spiraea tomentosa is a deciduous shrub in the rose family, forming upright, slender stems 2-4 feet (60-120 cm) tall in spreading colonial clumps. The stems and the undersides of the leaves are covered in a dense, rusty to whitish wool. The leaves are oval, 1-2.5 inches (2.5-6 cm) long, with toothed margins, dark green above and felted beneath. Tiny rose-pink to purple flowers are packed into narrow, steeple-shaped clusters 4-8 inches (10-20 cm) tall at the stem tips, opening from the top downward in mid to late summer. It grows in wet meadows, bogs, pond margins, old fields, and damp acidic ground across eastern North America. The plant spreads by rhizomes and self-seeding to form thickets in open, moist sites. Flowers attract bees, butterflies, and other small pollinators over a long summer season. The dried flower spikes and seed heads persist into winter, turning brown. Its spreading roots can colonize beyond a planted area, and it declines in dry soils and deep shade. Old stems become woody and respond to periodic renewal at the base.
Native Range
Native to eastern North America, from eastern Canada south to Georgia and west to the Great Lakes and Arkansas, in wet, acidic ground.Suggested Uses
Used in rain gardens, pond and stream margins, wet meadows, and bog plantings. Planted for erosion control and pollinator habitat on damp, acidic ground. Its colonial spread suits naturalized wet areas rather than small formal beds.How to Identify
Appearance
Size & Dimensions
Height2' - 4'
Width/Spread2' - 5'
Reaches mature size in approximately 3 years
Bloom Information
Flowers from July to September, in the heat of mid to late summer. The narrow pink clusters open from the top downward over several weeks. Brown seed heads follow and persist into winter.
Detailed Descriptions
Flower Description
rose-pink to purpleFoliage Description
dark green above, woolly beneathGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Grows in full sun to part shade in consistently moist to wet, acidic soil. It tolerates poor, boggy ground and seasonal flooding that many shrubs cannot. Plants spread by rhizomes to form colonies, so they suit naturalized wet areas rather than tidy borders. No fertilizer is needed in moist organic soils. It declines in dry soil and flowers sparsely in deep shade. Cutting older stems back in late winter renews the clump and improves flowering.Pruning
Stems can be cut back in late winter or early spring before new growth begins, since flowers form on the current season wood. Removing the oldest woody stems renews the clump. The spreading rhizomes can be cut back at the edge to keep the colony in bounds.Pruning Schedule
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winterearly spring