Kerria japonica, Japanese Kerria, is a deciduous flowering shrub often used in shrub borders. For best results, get facts and information on how to care for these fine-textured shrubs as it is important to choose the right shrubs.
Growing Kerria Japonica
Japanese kerris grows in Zones 5-9 and will grow in full sun to light shade. It will grow in Zone 4 in areas with good snow cover, but there will be some dieback. You can reduce winter damage by planting in a protected area with well-drained soil.
Kerria Japonica has an upright form that reaches 3-6’h x 6-9’w. It has bright yellow flowers that appear in late April and May, with sporadic bloom after the primary blooming occurs. In sun the flowers fade to a bleached out color. The shrub has distinct bright kelly green stems in winter that add to the winter landscape.
Use Kerria varieties in shrub borders or as a foundation plant. It suckers freely and can colonize areas. It does best in loamy, well-drained soil to part shade.
Caring for Japanese Kerria
Transplant balled-and-burlapped or container grown plants in early spring. Maintain an even water supply throughout the growing season. If fertility levels are too high, plants become weedy with fewer flowers. Plants that are cut back to the ground should be fertilized with plant food, such as Miracle-Gro, or mulched with compost or rotted manure.
Prune to shape right after flowering. Pruning out dead branches will keep the plants neat and in good bloom. It will flower on the previous year’s growth. Periodic rejuvenation by cutting plants to the ground can be helpful.
Propagation is done in summer or fall by taking cuttings. You may also divide clumps in the fall.
Pests and Diseases are not a serious problem, but leaf spot and twig blight can show up, but the damage is only cosmetic and will not hurt the plant.
‘Plentiflora’ has ball-shaped double flowers.
‘Variegata’ has single flowers, and leaves deeply margined in whie.
‘Shannon’ has larger blooms that appear earlier than the species.
‘Golden Guinea’ has single flowers.
‘Kin Kan’ stems turn yellow in winter and have thin green stripes.