In short
- One of the few shrubs that flower well in partial shade and shade.
- Golden-yellow flowers open in April and May.
- Bright green, angular stems adorn the garden in winter too, after leaf fall.
- Very hardy (USDA 4) and undemanding; spreads by suckers.
- Flowers on last year's wood — prune immediately after flowering.
Botanical data
- Family
- Rosaceae (Rosaceae)
- Height
- 1.5–2.5 m
- Width
- 1.5–2.5 m
- Habit
- Spreading
- Growth rate
- Fast
- Position
- Full sun, Partial shade, Shade
- Soil
- Loamy, Humus-rich, Sandy
- pH reaction
- pH 5.5–7.5
- Moisture
- Moderate
- Bloom
- April–May
- Hardiness
- USDA 4a–9b
- Propagation
- From cuttings, By division, By runners
Characteristics
A shrub 1.5–2.5 m tall with thin, arching, bright green and angular stems that stay green through winter. The leaves are ovate, sharply toothed and light green. The flowers of the species are single, five-petalled and golden-yellow; the most widely grown cultivar, Pleniflora, has double, pompom flowers. The plant spreads by root suckers, forming loose clumps.
Growing and care
Watering
A tolerant plant; once established it copes with occasional drought. Water in heat and in the first year after planting. It does not tolerate prolonged waterlogging.
Fertilizing
Undemanding; a spring mulch of compost is enough. Excess nitrogen produces lush growth at the expense of flowering.
Planting
A site in partial shade or shade (in full sun the flowers fade quickly), average, free-draining soil. Allow room for root suckers.
Pruning calendar
Pruning group: Spring-flowering shrubs
What and how to cut
Right after flowering each year, cut out 1/4–1/3 of the oldest shoots at the very base, and shorten the spent shoots back to a young side branch. This keeps a steady supply of young shoots coming from the bottom.
Immediately after flowering (May–June).
What not to do
Don't prune in winter or early spring before flowering — you'll remove the ready-formed buds and there will be no flowers. The right window is only the brief moment right after flowering. Don't shear them flat like a hedge either — you'll ruin the natural shape and the flowering shoots.
Companion plants
Good companions
They tolerate the same shady site and cover the bare base of the shrub, making a naturalistic, woodland planting with it.
Their blue contrasts beautifully with the yellow flowers of kerria and falls in the same spring flowering in partial shade.
Bad companions
Kerria produces numerous root suckers and quickly overwhelms weaker, slow-growing neighbours.
The evidence level indicates whether the relationship is backed by research, observation, or gardening tradition.
Toxicity
| For whom | Level | Notes |
|---|---|---|
| Humans | None | — |
| Dogs | None | — |
| Cats | None | — |
History and origin
The genus name honours the Scottish plant collector William Kerr, who brought the shrub into cultivation in Europe in the early 19th century. In Japan the kerria has been planted in gardens for centuries; as the sole member of its genus, it is an easy-to-grow, traditional spring shrub.
Uses
For shady borders, woodland edges and naturalistic gardens, where other shrubs flower poorly. Planted singly or in groups; valued for its early flowering and decorative stems that are evergreen in colour (not in foliage).
Trivia
- The leafless, bright green winter stems carry out photosynthesis and decorate the garden in the dead season.
- The double-flowered cultivar Pleniflora is almost sterile and offers pollinators less than the single flowers of the species.
Frequently asked questions
Does kerria flower in shade?
Yes, it is one of the few shrubs that flower well in partial shade and even in shade. In full sun its yellow flowers fade quickly, so a lightly shaded site is actually recommended.
Why are kerria's stems green in winter?
The bark of the young stems contains chlorophyll and carries out photosynthesis, so it stays bright green even after leaf fall. This is a valuable ornamental feature in the leafless winter garden.
How do you keep kerria from spreading?
The plant produces root suckers and, over time, wide clumps. Surplus suckers are cut out or dug up in early spring; planting it in a spot with room to spare makes maintenance easier.
Sources
- Plants of the World Online (POWO)Database (GBIF, POWO…)
- RHS — Kerria japonicaInstitution / botanical garden
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