I don't think you can separate dogwood. Most shrubs are like trees and have one root system. You would probably kill it if you tried. It is not like a perennial that comes from the ground every year

You can however start new plants from the seed.

Hi:

If it is a multi stemmed plant it may be divided assuming the stems are coming out of the soil. A very safe method is to take cuttings, they root easily and are much faster (and truer) than seed.

Cheers,
MG

Here is a link that might be useful: Our website

Both MG and Oil Painter are right. This is a shrub. If it bears seeds, it grows easily from seeds. However best way to propagate this plant is by cuttings. If you take the steps to do the cuttings now, set aside in indirect sun and by the end of summer you will have several new plants. (In fact it's the best time now to do these things with many woody plants)

I like this shrub by the way. I have 4 of it planted in a wet and dark shadowy area of my yard. It's so far behaved very well.