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Japanese meadowsweet (Spiraea japonica)

Spiraea japonica is an upright to semi-upright, multi-stemmed deciduous shrub and a perennial deciduous woody plant.

LightIt grows in full sun to partial sun and prefers ample sunlight.
WaterDuring the growing season it needs ample or regular moisture but should not remain waterlogged for long periods, and it prefers a moist, well-drained growing medium.
TemperatureSources differ, with limited evidence indicating cold tolerance to about -20 °C. It is generally reported to be frost hardy. Its USDA hardiness range is reported without specifying numerical zones here.
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Japanese meadowsweet illustration

Overview

Spiraea japonica is an upright to semi-upright, multi-stemmed deciduous shrub and a perennial deciduous woody plant.

Origin and habitat

Sources differ on its native range, describing it as native to temperate East Asia, principally China, Japan, and the Korean Peninsula. It occurs in habitats including riverbanks, stream margins, wetlands, forest edges and clearings, grassy slopes, valleys, and rocky or gravelly ground, as well as disturbed sites such as roadsides, within temperate East Asian climates.

Characteristics

Sources differ on mature height, placing it at about 20–200 cm, while mature spread is 91–200 cm; growth is moderate to fast. The deciduous leaves are simple and alternate, ranging from lance-shaped to ovate or broadly ovate, with serrated margins and green coloration; leaf shape, size, and hairiness are notably variable. Many small flowers form relatively flat clusters at branch tips, principally pink to red but sometimes white, with flowering extending to after midsummer. The fruit is reported to be a small, glossy follicle that splits open at maturity to release seeds.

Light

It grows in full sun to partial sun and prefers ample sunlight.

Watering

During the growing season it needs ample or regular moisture but should not remain waterlogged for long periods, and it prefers a moist, well-drained growing medium.

Temperature and dormancy

Sources differ, with limited evidence indicating cold tolerance to about -20 °C. It is generally reported to be frost hardy. Its USDA hardiness range is reported without specifying numerical zones here.

Growing medium and mounting

It adapts to various soils, including chalk, clay, loam, and sand, while preferring fertile, moist, well-drained loam and tolerating acidic, neutral, and alkaline conditions.

Propagation

It is reported to be propagated from seed, stem cuttings, or suckers.

Common problems

It may be affected by aphids, leaf-rolling moths, and scale insects. Prolonged soil saturation is unfavorable to growth; in some introduced regions it can escape cultivation, self-seed, or form dense thickets through root suckers and may become invasive. It prefers ample moisture during growth but does not tolerate prolonged waterlogged soil, while having some drought and cold tolerance.

Identification

Slender, much-branched stems form a shrub with simple, alternate, serrated leaves and conspicuous, flat pink-to-red flower clusters at the tips of current-year shoots.

Photos

Spiraea japonica
📷 Paul Hermans · CC BY-SA 3.0 · source

Sources