You can dig out the unwanted suckers now to reduce the
overall spread of the plants or wait until spring – your call.
Digging out the unwanted suckers is less likely to push new growth
at this time of year than pruning. Pruning is better delayed until
shrubs and trees are dormant because plants respond to pruning by
sending out new growth. At this time of year, that tender growth is
likely to be killed by winter cold.
Kerria grows vigorously (hold the fertilizer!) and it
is common to find a number of dead stems in the center of overgrown
specimens. These can be removed any time you find them. Kerria
produces next year’s flower buds as it finishes blooming, known as
“blooming on old wood.” If you prune after those buds are set, you
will remove next year’s blooms. Although you might miss a year of
flowering, it is good practice to rejuvenate kerria periodically by cutting it to the ground in March. When it regains some
growth after such treatment, thin the resulting stems to allow for
better air circulation and to allow light into the center of the
The variegated form (Kerria japonica ‘Picta’) is less
vigorous than the all green forms and may not require such drastic
pruning. It inevitably produces some plain green shoots that
should be removed as soon as you notice them. Since the green stems
are more vigorous than the variegated ones, they can quickly take
over a variegated plant.
Saving coleus over the winter
Why roses change color