Tens of thousands of cultivars of Dianthus have been bred for garden use and commercial greenhouse production. Divided into carnations and pinks as well as many subgroups this genus of over 300 species is mostly annuals and biennials from all over Europe and Asia with at least one species native to arctic North America.
With so many species and cultivars conditions and hardiness vary wildly but most species prefer full sun and well-drained, neutral to slightly alkaline soil (although some prefer acidic conditions.)
Primary cause of cultivation failure is poor drainage.
These dianthus are Sweet William growing in North Carolina on the border of zone 7/8. The grow to 1 - 2 ft. Flowering in late spring to summer they are treated as biennials and can be raised from seed each year. The flowers are a variety of colors and can also be two-toned.
They are excellent for filling gaps in borders, good for massed planting and are good for cutting.
Very easy to grow since they are not fussy about soil; they do like a sunny situation.
One of my gardening books says Sweet William grows best in zones 3 -9; another says 4 - 10.