🌼 Grow Guide: Kerria japonica and Kerria japonica ‘Pleniflora’
Bright spring flowers for easy, informal gardens
🌿 Plant Overview
| Feature | Kerria japonica (Single) | Kerria japonica ‘Pleniflora’ (Double) |
|---|---|---|
| Family | Rosaceae | Rosaceae |
| Type | Deciduous shrub | Deciduous shrub |
| Hardiness | RHS H6 (–20°C to –15°C) | RHS H6 (–20°C to –15°C) |
| Height & Spread | 1.5–2.5m × 1.5–2.5m | 2–3m × 2–3m |
| Flowers | Single, open, yellow blooms | Fully double, pom-pom-like yellow blooms |
| Flowering Time | April–May (sometimes again late summer) | April–May (sometimes few later flowers) |
| Foliage | Bright green, toothed leaves | Light green, toothed leaves |
| Scent | Mild | Mild |
🌱 Planting
- Best Time to Plant: Autumn or spring
- Soil: Moist but well-drained soil
- Soil Type: Grows well in loam, clay, chalk, or sandy soils
- Not Suitable For: Very dry, shallow soils without soil improvement
- pH: Neutral to slightly alkaline (tolerates slightly acidic)
- Light Requirements:
- Kerria japonica: Thrives in partial shade to full shade
- ‘Pleniflora’: Prefers partial shade; flowers better with more sun
- Spacing:
- Kerria japonica: 1.5–2m apart
- ‘Pleniflora’: 2m apart
Tip: Improve clay or sandy soil with organic matter like compost or leaf mould before planting.
🌸 Seasonal Interest
Both types flower in April–May, bringing a cheerful splash of yellow just as spring moves into early summer.
- Kerria japonica sometimes reblooms lightly in late summer.
- Leaves turn pale yellow in autumn before falling.
🌦️ Care & Maintenance
Watering
- Water well in the first growing season.
- Established plants are moderately drought-tolerant.
Feeding
- Mulch with compost or leaf mould in spring.
Pruning
- After flowering (May–June):
- Remove about a third of the oldest stems at ground level.
- Thin congested growth to maintain the arching shape.
- For ‘Pleniflora’:
- Needs more pruning to control suckering and spread.
Note: Always prune immediately after flowering to ensure good blooms for the next spring.
Pests & Diseases
- Generally pest- and disease-free.
- Coral spot fungus may occasionally affect old wood — prune out affected stems promptly.
🪴 Container Growing
- Suitable for large containers (minimum 50cm deep).
- Use a loam-based compost with extra organic matter.
- Ensure excellent drainage.
✂️ Propagation
- By Suckers: Lift and pot up rooted suckers in autumn or spring.
- By Cuttings: Take softwood cuttings in late spring or semi-ripe cuttings in summer.
- By Division: Divide suckering clumps in spring if needed.
🔁 Troubleshooting
| Problem | Likely Cause | Solution |
|---|---|---|
| Weak flowering | Too much deep shade | Move to lighter spot (especially for ‘Pleniflora’) |
| Leggy, tangled stems | No pruning | Cut oldest stems back yearly |
| Unwanted spreading | Suckering | Cut suckers back at base |
| Brown patches on stems | Coral spot fungus | Remove and destroy affected wood |
🌼 Comparison Chart
| Feature | Kerria japonica (Single) | Kerria japonica ‘Pleniflora’ (Double) |
|---|---|---|
| Flower Type | Single, open, yellow blooms | Fully double, pom-pom-like blooms |
| Flowering Time | April–May (sometimes later) | April–May (few flowers later) |
| Plant Size | 1.5–2.5m × 1.5–2.5m | 2–3m × 2–3m |
| Light Preference | Partial shade to full shade | Partial shade to sun (needs more light) |
| Growth Habit | Arching, graceful | More vigorous, spreading by suckers |
| Shade Tolerance | Very good | Moderate – flowers less in heavy shade |
| Pruning Needs | Moderate | Higher (annual control needed) |
| Wildlife Value | Good (single flowers attract pollinators) | Lower (double flowers less accessible) |
| Maintenance Level | Low | Moderate |
🌼 Which One Should You Choose?
- Choose Kerria japonica (single-flowered) if you want a wildlife-friendly shrub that can brighten deep shade with very little care. It’s a great choice for informal gardens, shady corners, and natural woodland edges.
- Choose ‘Pleniflora’ if you love massive displays of cheerful yellow pom-poms and don’t mind doing a little extra pruning each year. It’s perfect for sunny to lightly shaded spots where it can show off its bold spring blooms.
Both are hardy, reliable, and bring low-maintenance colour to gardens just when you need it most!
