Spirea

Spirea (Spiraea japonica)

Japanese Spirea, Japanese Meadowsweet

Full sun to part shade; medium moisture, well-drained; tolerates clay once established; pH 6.0–7.5.

2–5 feet tall and 2–5 feet wide depending on cultivar; blooms May–June with flat-topped corymbs of pink to deep rose flowers; many cultivars produce golden, orange, or red new foliage; repeat bloom possible with deadheading; deciduous; spreads by suckering and self-seeding.

Propagation: softwood cuttings root readily in early summer; division of established clumps in early spring or fall.

Native region: Not native to Tennessee; introduction from Japan, China, and Korea. Can naturalize in disturbed areas and stream banks in the eastern United States.

S. japonica is among the most commonly planted deciduous shrubs in Middle Tennessee, valued for low maintenance and reliable bloom. Hard rejuvenation pruning — cutting the entire plant to 6–8 inches in late winter — is the single most important maintenance practice, restoring vigor and tight form to plants that become open and floppy with age. Without periodic renewal pruning, spireas develop a tangled, unproductive interior within 5–7 years. Spirea aphid (Aphis spiraecola) causes leaf curl and stunted new growth in spring, particularly on yellow-foliage cultivars such as 'Gold Mound' and 'Goldflame'; insecticidal soap at first sign is effective. Powdery mildew can develop on foliage in humid, low-airflow sites during July and August in Middle Tennessee — adequate plant spacing prevents most outbreaks.