Name: Kerria japonica aka Japanese Kerria
Type of Plant: This is a shrub with bright green stems and bright yellow flowers that is hardy in Zones 4-9. In most areas this plant grows to about 5 feet tall and 8 feet wide. Some have single flowers, but ‘Pleniflora’ is a double-flowered variety that is especially popular and easy to find.
Why I Love/Hate this plant: I love this plant because it grows in part sun to full shade. The deer don’t eat it, and it grows well in a variety of soil conditions. I also love the arching stems that are bright green in the winter, adding color and an almost grass-like appearance during the cold season. But of course, it’s the cheerful, yellow flowers that really charm me. I’ve heard people compare them to marigolds.
A Word to the Wise: This is a suckering shrub, meaning it spreads by creating new stems to all sides, similar to the blue hydrangea. Plant it where it has room to spread out, but once it’s as large as you want it, prune out these side stems by cutting them to the ground at any time during the year. If you don’t like plants that travel, this is not the shrub for you.
The only way to prune this plant is to take off dead canes, and remove those that are spreading out too far at ground level. This is a plant that should never be sheared! In other words, don’t make this into a green meatball…its fountain shape is one of the things that makes it a beautiful plant.