Red twig dogwood, or red osier, known botanically as Cornus sericea, is a flowering and fruiting shrub with pronounced cherry red branches. As it is a deciduous shrub, the leaves turn color in the fall before dropping away to expose the red twigs and contrasting white berries. The younger the branches are, the more vibrant their red hue, so North Carolina State University recommends severe rejuvenation pruning to encourage a profusion of rich color. However, the plant does not require regular pruning save the removal of damaged or diseased tissues.
Prune your red twig dogwood either in the spring after the last frost but before bloom or immediately following bloom in mid- to late summer. Though this is largely a matter of convenience and preference, pruning in the spring before bloom will obviously lessen, to some degree, the amount of buds available to mature and flower.
Look over the shrub carefully each year to assess whether there are any broken or dead branches, diseased tissues or branches that are abrading one another and may be ripe for insect or disease activity. Cut back any of these that you come across, cutting back to the point of healthy tissue just above a leaf node or bud, or down to where the branch connects to its parent branch, or down to the crown of the plant just above the soil line.
Rejuvenate the shrub and increase the number of young, bright red branch shoots by pruning away up to one-third of the oldest shrub branches down to the crown of the plant at the soil line. Distribute these cuts throughout the shrub so that new growth occurs and fills in the shrub structure evenly.
Reduce the height and spread of the dogwood shrub, if absolutely necessary, by judiciously shortening the branch tips to the desired length. Cut branch by branch and never remove more plant tissue than required nor more than one-third of the shrub's overall volume. Place all cuts on the bias 1/4 inch above a leaf axil or bud.