You can just prune a third of the stems back to ground level in March rather than all of them, if you want some height - note they should be in full sun for the best colour to develop. Obviously, the uncut stems will not be as red in winter as the newer stems.

Or . . . we are lucky enough to have two, so cut one back to about 12" every other year, and the other, the other year, if that makes sense? They are in semi-shade.

I cut mine almost to the ground and it grows back to at least five feet over the summer. Its only the new stems that are red.

Thanks Bamboo, Sheilabub and Steragram.
It sounds as if i will have to play around with cutting back, just experiment and see what suits. Yes Sheilabub, i agree they should have a bit more shade than i can offer them - like none at all - but as we planted well over a hundred dogwoods, the wild variety, in our new native hedge 5 yrs ago, which all managed to survive and many of them are now magnificent bushes, gives me hope that the cultivars might be equally adaptable.

Resi, if you look at my answer, you'll see that I say they achieve their best colour in full sun. And also, Sheilabub does not say they need shade, just that hers are growing in partial shade.

i do realize about the full sun Bamboo, but full sun in the uk and full sun here are two very diffferent beasts.
in my experience here the dogwoods struggled hard to establish themselves but now the hedge is creating some of its own shade they are romping away.

Oh blimey, sorry, I didn't notice where you were, made the assumption you were in the UK...