Japanese Kerria covers itself in flowers that can be single or double depending upon the cultivar. Most blossoms are yellow or gold, but white is also available. Photo submitted by the University of Tennessee Department of Plant Sciences. >>>download photo

Submitted by Dr. Susan Hamilton


The world of horticulture has always been a bit of confused regarding the name of Japanese Kerria. This showy springtime shrub is not native to Japan, rather it is from central and western China.

Known to 18th century European plant classifiers only by written descriptions that originated from Japan, the plant was mistakenly thought to be native to Japan. In reality it had been introduced there. To add to the confusion, the plant's genus was also mistakenly classified. Since it has incomplete flower parts, early classifiers wrongly assigned it to the Linden family. Later scientists realized that the plant belonged in the Rose family, and they correctly discerned that is the only species in an entirely new genus.

The new genus was named Kerria in honor of William Kerr, who in 1804 was collecting plants in China for England's Kew Gardens. Still, the misnomer 'Japanese' Kerria persists in both the common and scientific names.

Kerria peaks in bloom during April and May but will flower sporadically throughout the summer. It covers itself in flowers that can be single or double depending upon the cultivar. Most blossoms are yellow or gold, but white is also available. Flowers are typically 1 to 2 inches across.

Kerria grows 3 feet to 6 feet tall and has a spread of 6 feet to 9 feet. It thrives in a partly shady area with moderately moist soil. It's known to tolerate dry conditions well and is considered a durable plant.

Although it is a good shrub for brightening up a shady area of the landscape, its deciduous nature can result in an unkempt appearance if the plant is not pruned occasionally. Prune stems one third to one half in mid summer or winter. Stems remain green throughout the winter, which can provide interest in the dormant landscape.

While this plant can be used as a single specimen, it is quite impressive when used in mass.

Numerous cultivars are available: 'Albiflora' - white flowers; 'Golden Guinea' - large, golden yellow, single flowers; 'Picta' - single flowers, but the leaves have white margins; 'Pleniflora' - double flowers; 'Shannon' - large, single, yellow flowers; and 'Superba' - single yellow flowers.

Susan Hamilton is an associate professor of plant sciences on the faculty of the University of Tennessee Department of Plant Sciences. She is also director of the UT Gardens, which are located in Knoxville on Neyland Drive. The gardens are open to the public year round from dawn to dusk. More information is available at http://utgardens.tennessee.edu

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