We planted a double kerria in July 2017. This year I notice a circle of new growth about 20 centimeters from the original clump. Should I remove this new growth and the suckers supporting it and if so, how do I do that without damaging the plant? I also notice that the last 30 cm of a number of the thickest limegreen stems on the original plant seem to be dead. Do I cut off or break off the dead section or cut those stems right back to the ground?
Thank you for contacting the Toronto Master Gardeners concerning your Kerria.
This beautiful shrub also known as Japanese rose produces lovely yellow flowers in the spring. It is important to know the correct time to prune this shrub. Kerria blooms on old wood, therefore you should prune just after its spring flowering is over. You may be lucky and have a second flowering later in the season. If you do happen to get a second flush of flowers, do not prune after this second flowering since you will be removing next years flower buds.
Cut out any damaged or dead shoots to ground level. You are correct, Kerria spreads by suckering; in fact, the main problem with this plant is that it spreads so vigorously. Prune any suckers that grow around the base of the plant to the ground. If you fail to cut back the suckers you will find that your plant will grow wider every year.
You may also prune the shrub’s shallow spreading root system by root pruning. How to Prune Kerria Roots gives step by step instructions on how to accomplish this.
Heres to continued enjoyment of this beautiful shrub.