I have had red twig variegated dogwood shrub for about 15 years. Since last year some of the twigs are bearing non-variegated leaves. How do I make it go back to being a complete variegated shrub?
Not all variegated plants are stable and can often began to revert to green coloration.
It is best to trim out any branches that are growing without the variegation.
Here is a link with more information.