Spiraea douglasii aka Rose Spirea

Spiraea douglasii is a deciduous shrub in the rose family. Common names include Douglas spirea, rose spirea, and hardhack. It grows wild in western Canada and the western United States. Its range reaches from southeast Alaska to northern California. It also grows in parts of Idaho. Wild plants grow beside streams, marshes, and wet meadows. They also grow in wet forest soils, sometimes in drier sites.

This upright shrub spreads by suckers and can form dense thickets. Garden plants reach about 5–8 feet (1.5–2.5 metres) tall and wide. Other accounts give heights of 2–7 feet (0.6–2.1 metres). Its slender twigs start pale yellow-brown, then turn reddish-brown with age. Older twigs may have slight ribs. The reddish-brown bark is smooth but may peel in strips. Leaves grow in an alternate pattern along the stems. Each leaf is oblong to oval, with a short stalk. Teeth line the upper edge, while the base stays smooth. The upper surface is green; fine pale hairs cover the underside.

Small pink to purplish-pink flowers appear in early summer. They crowd into upright panicles at the stem tips. These fragrant clusters can look powdery from their tiny projecting stamens. The blooms attract butterflies and give the shrub its main show. Small brown follicles follow the flowers in upright clusters. The brown seed heads stay on the plant after flowering.

Grow this shrub in sun or partial shade. It grows well in most moist soils and tolerates wet sites. Suitable soils include chalk, loam, and sand across a broad pH range. The RHS rates its hardiness H6; Oregon State lists USDA Zone 5. It needs little routine care, though suckers can spread beyond planting space. Use it beside ponds, along streams, or in low ground. Its spreading habit suits wild areas better than formal beds. It also suits informal gardens, banks, and slopes. Cut overgrown plants back hard just after flowering.

Serious pest and disease trouble is uncommon, but problems can occur. Aphids and scale may attack it. Possible diseases include fireblight, leaf spot, powdery mildew, and honey fungus. Some plants may suffer dieback. PFAF lists no known edible uses and no known hazards. This does not establish that every part is safe to eat. It records past use of seed infusions for diarrhoea. People have also used the branches to make brooms.