My experience with Phlox Divaricata is that it is a small, very slow growing and slow multiplying sweet perennial.

I think it would look nice next to hostas and would do well planted with daffs. I would imagine the phlox would go dormant after blooming and the hot temps and dryer weather sets in. I seldom see mine after it blooms, but it is in the (wild) woods.

Mine is of the nature in the pic linked below...and does not have a spreading nature.

Sue

Here is a link that might be useful: Phlox divaricata at Missouriplants