Kerria Japonica is one of the few plants that will bloom profusely in a shaded area. It blooms on old wood in early-to-mid spring; prune just after its spring flowering is over. A second flowering later in the growing season is not unusual, but it is too late to prune at that point (you would lose out on next year's flowers because you would be removing the flower buds). Prune out dead branches as you find them. Old plants in need of rejuvenation pruning may be cut down to ground level. Japanese rose spreads by suckering; remove suckers as they occur if you wish to control its spread. In fact, the main problem with this plant is that it spreads so vigorously (a drawback for those seeking low-maintenance landscaping. Stay ahead of it with regular sucker removal.