Thunberg's lespedeza
Lespedeza thunbergii · Fabaceae
📷 VoDeTan2 · CC BY-SA 3.0
The gardener's calendar
Thunberg's lespedeza is in full bloom: enjoy it, watch watering in hot weather and let spent flowers feed pollinators before pruning.
ID card
- Foliage
- Deciduous, composed of small leaflets
- Flowering
- August to October, pink to purplish flowers
- Adult size
- 1.5 to 2 m in height, spreading bushy form
- Growth
- Fast to moderate
- Hardiness
- Hardy to around -15°C
- Origin
- Southeast Asia (Japan, China)
- Soil type
- Well-drained soil, undemanding
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability high.
Expert tips
The key tip
Lespedeza thunbergii explodes with mauve-pink flowers in autumn if you cut it back hard in February to 30–40 cm from the ground. It regrows from very little wood, which is completely normal and desired.
The common mistake
Leaving it standing through winter or pruning too lightly: it becomes a big exhausted shrub with little or no new flowers and dead wood at the core.
The pro's trick
A light potassium fertilizer boost in July (after the first summer flowering of other Lespedezas) stimulates a strong autumn flush in September-October.
Seasonal watch
Early autumn with harsh frost: if hard freezes arrive as early as September, the autumn flowering stops abruptly.
Care
Watering
Water regularly during the growing and flowering period, especially in summer. Reduce watering in winter. Prefer moist soil but never waterlogged to prevent root rot. Good drainage is essential.
Light exposure
Place your lespedeza in a sunny location that receives at least 6 hours of direct sunlight daily. It tolerates partial shade but flowers more generously in full sun. Avoid deep shade which slows fruiting.
Pruning and training
Prune after flowering in autumn or late winter, before growth resumes. Remove dead or poorly oriented branches to open up the center of the bush. Light pruning every 2-3 years maintains shape and stimulates future flowering.
Fertilization
Apply balanced fertilizer in spring when growth resumes. Reduce nitrogen applications to promote flowering. Moderate fertilization is sufficient, as this plant doesn't require many nutrients.
Soil type
Lespedeza prefers well-drained, light, slightly acidic to neutral soil. It adapts to poor or sandy soils and tolerates chalky soils well. Enrich with compost at planting time if the soil is very depleted.
Diseases and pests
This plant is generally robust and rarely affected by diseases. Occasionally watch for aphids at the start of the season. Excess moisture can promote rot; ensure good drainage and air circulation around the foliage.
Did you know?
Thunberg's lespedeza is named after Swedish botanist Carl Peter Thunberg, who explored Japan and China in the 18th century. In Asia, this plant has long been cultivated for its elegant form and spectacular late autumn flowering. Its tendency to reflower late in the season makes it a valuable nectar source for bees and butterflies in seasonal decline.
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.