I have always been told to plant grafted roses so that the union (where graft meets scion) is about 2 inches ABOVE the soil line. But I recently was told that the proper way to plant a grafted rose is with the union well BELOW the soil line. Which is correct? Does it matter? I garden in Zone 6.

Below ground protects the rose graft from freeze damage. Paul Zimmerman in a warmer zone then yours recommends planting below ground. He has a video on this at -
paulzimmermanroses.com

Annie - As someone who kills roses on a regular basis, I always plant mine BELOW the soil line. As deep as I possibly can (depends on how lazy I am as to how deep I dig the hole). Plus I always mulch on top of that for winter protection. And I'm zone 5 (sometimes zone 4, depending on the winter.. this has been a colder winter for us).

It's only in the warmest zones that the graft union is kept two inches above ground level.