Douglas spirea
Spiraea douglasii · Rosaceae
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around douglas spirea and prepare for winter.
ID card
- Foliage
- Deciduous
- Flowering
- July to September, pink-magenta flowers
- Mature size
- 1.5 to 2 m tall × 1.2 to 1.5 m wide
- Growth rate
- Fast
- Hardiness
- Zone 4 to 8 (-30 °C)
- Origin
- North Pacific Coast of North America (Oregon, California, British Columbia)
- Soil type
- Fresh to moist, well-drained soil
Care
Regular watering
Douglas' Spiraea appreciates fresh, moist soil. Water regularly, especially during summer dry periods and the year following planting. In naturally moist soil (riparian or wetland areas), watering will be less critical. Avoid prolonged drought, which would slow flowering.
Bright exposure
Place your Spiraea in full sun (6+ hours) for generous and colorful flowering. It tolerates partial shade, but flowering will be less abundant. In very hot climates, light afternoon shade can prevent water stress.
Soil preparation
Prepare rich soil, slightly acidic to neutral, enriched with organic matter (compost, peat). Douglas' Spiraea prefers naturally moist soil or amended soil. In overly chalky or very dry soil, improve the structure with compost when planting.
Pruning and shaping
Prune after flowering (late September-October) or in late winter to remove dead branches and rejuvenate the shrub. Remove about one-third of the height to maintain a nice compact form. Spiraeas tolerate pruning well and restart vigorously in spring.
Nutritional input
An application of well-decomposed compost in spring is usually sufficient. In poor soil, a balanced fertilizer (NPK) in spring will promote vigor. Avoid excess nitrogen, which reduces flowering in favor of foliage.
Health and prevention
Douglas' Spiraea is generally robust. Watch for aphids and spider mites in dry conditions. Powdery mildew can appear in humid, confined atmospheres; ensuring good air circulation prevents this problem. No serious disease particularly affects this species under optimal conditions.
Did you know?
Douglas' Spiraea is named after David Douglas, a 19th-century Scottish botanist who explored the North American Pacific coast and brought many species to Europe. In its natural habitat, it grows in wetlands and open forests, forming spectacular bright pink masses at the height of summer, which explains its growing appeal in modern landscape gardening.
Where to buy it
Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.
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Tips generated and checked by Viridia — adapt them to your local climate.