Spirea

Sun

Full sun gives the most flowers and strongest foliage colour; tolerates partial shade but becomes looser and flowers less.

Water

Water regularly during the first growing season. Once established, water during prolonged dry spells; avoid constantly wet soil.

Soil

Adaptable to clay, loam or sandy soil if drainage is good. Prefers moderately fertile soil and tolerates a broad pH range.

Height

4-6 ft (1.2-1.8 m); many compact cultivars stay 1-3 ft (0.3-0.9 m)

Spread

4-6 ft (1.2-1.8 m); compact cultivars are often 2-4 ft (0.6-1.2 m) wide

Flowers

Flat clusters of pink flowers from early to midsummer, sometimes followed by scattered repeat flowers; some cultivars have white flowers.

Foliage

Small, pointed, toothed leaves, usually green. Cultivars may have yellow foliage or coppery new growth; autumn colour can include yellow, orange and red.

Growth

Moderate to fast

Care needed

Low

• Water deeply during dry weather in the first growing season, allowing the surface soil to dry between waterings.
• Apply 2-3 in (5-8 cm) of organic mulch, keeping it clear of the stem bases.
• Top-dress with compost in spring; avoid heavy feeding, which encourages soft, leafy growth.
• Remove spent flower clusters before seed develops, especially where seedlings are a concern.
• Pull unwanted seedlings while small and remove rooted shoots that extend beyond the allotted space.

Pruning. In late winter or early spring, remove dead wood and cut up to one-third of the oldest stems to the ground; flowers form on the current season's growth. Lightly trim after the main flowering flush to remove spent heads and encourage some repeat bloom.

Late winter

Thin out old stems and remove dead or damaged wood before new growth starts.

Spring

Plant where locally appropriate, water thoroughly and mulch around the root zone.

Late spring

Check tender shoots for aphids and rinse off small colonies with water.

Early summer

Water young plants during dry spells and check that nearby plants are not crowding them.

Midsummer

Trim off fading flower clusters before seed ripens.

Autumn

Remove unwanted seedlings and replenish mulch where it has thinned.

• Use compact cultivars along paths or at the front of mixed borders for a low, rounded outline.
• Plant repeated groups with ornamental grasses and summer perennials to link a border together.
• Use as a low informal hedge where it is not invasive, allowing room for its natural width.
• Pair golden-leaved cultivars with blue or purple flowers for foliage contrast.

Garden styles it suits: Cottage garden, Traditional, English country, Family-friendly, Low-maintenance and Small-space.

Plant it with: Catmint, Hardy geranium, Salvia, Daylily, Feather reed grass and Coneflower.

Wildlife: Flowers provide pollen and nectar for bees, flies and other insects. In regions where it is invasive, locally native flowering shrubs are a better choice because escaped spirea can displace native vegetation.

• Aphids can curl young shoots: dislodge them with a firm spray of water and avoid excessive nitrogen feeding.
• Powdery mildew may coat leaves in crowded, poorly ventilated sites: improve spacing, water at soil level and remove badly affected growth.
• Waterlogged soil can cause root decline and dieback: improve drainage or move the shrub rather than continuing to water.
• Sparse flowering and floppy growth often result from too much shade: move to a sunnier position and thin crowded stems.

Not known to be toxic to cats, dogs, horses or people; no part is recognised as a significant poisoning hazard. It is not an edible plant, and eating substantial amounts may cause digestive upset.

Where it spreads. Invasive in parts of the eastern United States, particularly the Mid-Atlantic, Appalachian and southeastern regions, including Pennsylvania, Virginia, Tennessee and North Carolina. It spreads by seed and can form dense patches along streams, woodland edges and disturbed ground.

• Birchleaf spirea (Spiraea betulifolia)

  Usually has broader, more rounded leaves resembling small birch leaves and white flower clusters, rather than the narrower leaves and typically pink flowers of Japanese spirea.

• Vanhoutte spirea (Spiraea × vanhouttei)

  Forms a larger shrub with arching branches covered in white flowers in spring; its leaves often have shallow lobes. Japanese spirea has a more upright, rounded habit and flowers in summer.

• White meadowsweet (Spiraea alba)

  Bears upright, elongated clusters of white flowers rather than broad, flat pink flower heads, and is commonly associated with moist ground.

Spiraea comes from the Greek speira, meaning a coil or wreath, while japonica means 'of Japan'.

Propagation. Root softwood cuttings in late spring or early summer to preserve a cultivar's characteristics. Seedlings may differ from the parent; avoid seed propagation where escape is a concern.

Accepted botanical name

Spiraea japonica

In the US and Canada

Introduced in Canada and the lower 48 states.

Native range

China North-Central, China South-Central, China Southeast, Japan, Myanmar, Taiwan and Tibet.

Measured

Average height 138 cm.

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