I don't have personal experience with the combination, but I think the white of Cerastium tomentosum, snow-in-summer, would look lovely under dramatic dahlias!

Brenda

Thank you for replying, Brenda. I was looking for some taller plants to combine with the larger dahlias, 'tho.
How long does cerastium bloom in CA?
Ginger

Old, and short, thread. Regardless, I'm thinking of putting violet dahlias along with some burgundy okra in one row of my garden; part of my spring vegetable/herb project is to incorporate more flowers for the aesthetic effects, but also to see what might assist in pest control.

I had a tall flat leafed parsley (Italian) along the fence with the dahlia = fantastic combo. Think it was the 2nd year the parsley grew as tall as the dahlia. Parsley re-seeded so had that combo several years.