The greatest beauty of the red osier dogwood lies in the shrub's branches and twigs. The bark of the red osier's newest growth turns green in summer, but when fall colours reveal themselves this dogwood shifts to red. The red colour lasts through the winter snows and makes a welcome contrast to a stark winter landscape. As stems age, coarser outer bark shields the coloured layers from view. Pruning stimulates the red osier to produce new and colourful stems for the next winter season.
Prune out only dead or damaged branches until the red dogwood is five or more years old. Cut the unwanted section of the plant back to the branch collar, a swollen ring of tissue near the junction with the limb or the trunk. Let the dogwood spread by allowing new shoots sprouting near the main stem to grow undisturbed.
Locate the older central stems of a mature red dogwood and trim them back as close to the ground as possible. Work without damaging the bark of adjacent stems. Summer foliage soon hides any visible stubs. Remove as much as one-third of the thicket by cutting out the older growth.
Repeat this renewal pruning every two to three years, always cutting out the oldest stems by shearing them back close to the ground.
Control the spread of the dogwood thicket by cutting unwanted shoots back to the ground at the border of the planting.
Remove dead or broken branches in late winter when the dogwood is dormant, but prune to encourage new growth in early spring when the plant is most vigorous. Give red osier dogwood plenty of room, since the shrub may grow into a thicket 10 feet tall with a spread of 15 feet. Cultivars of red osier provide other colour contrasts for the home landscape. Silver and gold dogwood grows variegated leaves rather than the normal solid green, and shows yellow bark in fall and winter. The bark of a similar variety called yellow-twig dogwood may sunscald after the summer foliage drops.
Trimming back the tops of stems causes the red osier dogwood to grow thicker top growth but gives the bush an unnatural appearance. The denser foliage may shade out and kill inner parts of the shrub. Using renewal pruning instead of top pruning protects the health of the dogwood.