If you are speaking about the Cornus species that has the typical dogwood flowers, I thought it would not survive here in zone 7, so I never tried it. Looks like your in a warmer zone than me. Did see it in Maine in zone 5.

As long as you can provide the proper growing conditions and avoid extended summer heat and humidity, it should grow fine in zone 7. It's not the winter temperatures that are a concern in higher zones but the summer conditions. A PNW zone 8 is pretty distinct from other zone 8's - generally quite cool here in summer and very low humidity. Bunchberry thrives here in a woodsy setting with organically rich, acidic soils and sufficient moisture. If you can replicate that, then give it a try.

It's one of the more popular groundcovers I sell and also one of the most pricey :-)