Rose spirea

Sun

Full sun to partial shade; flowering is best in sun where the soil stays moist.

Water

Prefers consistently moist to wet ground and tolerates seasonal waterlogging. Water during dry spells, especially while establishing.

Soil

Moisture-retentive loam, clay or peaty soil; prefers acidic to neutral conditions but tolerates a range of soils.

Height

4-7 ft (1.2-2.1 m)

Spread

4-7 ft (1.2-2.1 m) initially; suckering colonies can become much wider.

Flowers

Summer into early autumn; dense, upright, tapered clusters of rosy-pink flowers.

Foliage

Alternate, oval to oblong green leaves, toothed mainly toward the tips, with pale, felted undersides; sometimes yellow in autumn.

Growth

Fast in moist soil.

Care needed

Medium

• Pollinators
• Wildlife
• Low allergen

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Very tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1.6 ft (0.5 m)

2. After 1 year

   2.8 ft (0.85 m)

3. After 2 years

   4 ft (1.2 m)

4. After 3 years

   5 ft (1.6 m)

5. After 5 years

   5 ft (1.7 m)

   full size

About 3 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US and Canada

Invasive in

the UK

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Water deeply during the first growing season and whenever prolonged dry weather dries the root zone.
• Apply 2-3 in (5-8 cm) of organic mulch in spring, keeping it clear of the stem bases.
• Avoid routine heavy feeding; on poor soil, add a thin layer of compost in spring.
• Dig out unwanted suckers with their connecting roots before they establish beyond the planting area.
• Allow space for a colony rather than planting close to small, slow-growing plants.

Pruning. In late winter or early spring, remove dead stems and cut about one-third of the oldest stems to ground level; flowers form on the current season's growth. An overgrown colony can be cut back hard at the same time.

Late winter

Thin out old stems at ground level before new growth starts.

Spring

Plant into moist ground, water thoroughly and mulch around the root zone.

Late spring

Check the colony's edges and dig out unwanted suckers.

Summer

Water during prolonged dry spells; avoid letting newly planted shrubs dry out.

Early autumn

Remove spent flower heads before seed ripens where unwanted seedlings are a concern.

Late autumn

Plant or divide dormant suckers where the ground is workable and not waterlogged or frozen.

• Plant in broad groups beside ponds or streams, allowing room for a spreading colony.
• Use in rain gardens and seasonally wet depressions, away from drains and small borders.
• Combine with sedges, rushes and moisture-loving perennials for an informal wetland planting.
• Use as a loose summer-flowering screen along a damp boundary.
• Include in western North American native planting where its vigorous spread is appropriate.

Garden styles it suits: Pacific Northwest woodland, Bog garden, Wildlife garden, Rewilded, Cottage garden and Native hedgerow.

Plant it with: Tufted hair grass, Soft rush, Slough sedge, Western sword fern, Red-osier dogwood and Western columbine.

Wildlife: Flowers provide pollen and nectar for bees and other insects. Dense colonies offer shelter for small birds and other wildlife, particularly within its native range.

• Unwanted thickets: remove suckers with their connecting roots regularly, or choose a less spreading shrub for confined gardens.
• Powdery mildew: improve airflow, avoid overcrowding and keep roots adequately watered during dry weather.
• Aphids on soft shoots: wash off small colonies with water and leave predatory insects undisturbed.
• Leaf scorch or wilting in dry soil: water deeply and renew mulch; relocate plants if the site repeatedly dries out.

Not known to be toxic to people, cats, dogs or horses. No part is recognised as a significant poisoning hazard, but it is not a food plant.

Where it spreads. Spreads aggressively by underground stems, including within its native western North American range. It has become invasive in parts of the United Kingdom and Ireland and in parts of northern and central continental Europe, including Belgium and Germany; check local guidance before planting outside its native range.

• Steeplebush (Spiraea tomentosa)

  Also has upright pink flower clusters, but its young stems and leaf undersides have conspicuous rusty-brown woolly hairs rather than the whitish felt typical of rose spirea.

• Willow-leaved spirea (Spiraea salicifolia)

  Usually has paler pink, looser flower clusters and leaves that lack the dense whitish felt beneath. Hybrids can make identification difficult.

The species name douglasii honours Scottish botanist David Douglas, who collected plants in western North America.

Propagation. Separate rooted suckers during dormancy, taking a section of connecting root with each shoot. Softwood cuttings can be taken in early summer; seed is also possible, but plants may hybridise with other spireas nearby.

Accepted botanical name

Spiraea douglasii

In the US and Canada

Native in Alaska, Canada and the lower 48 states.

Native range

Alaska, British Columbia, California, Colorado, Idaho, Montana, Oregon and Washington.

Measured

Soil pH 5.5 to 7.5. Average height 200 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.