Because they do not like warm weather through summer much, sweet William, Dianthus barbatus, is appreciated more as a cool season annual from autumn into winter and even into spring. They can also be planted early in spring for color before summer warmth. They can sometimes survive as perennials in sheltered areas, particularly if mixed and hidden amongst other perennials and annuals. Deadheading (removal of deteriorating flowers) prolongs bloom.

New plants are easy to propagate from division, cuttings or layering of tired older plants. (Layering involves rooting prostrate stems by burying them slightly and them separating them when they have developed roots.) By the time the old plants become too deteriorated to salvage, the new cuttings or layers should be ready to replace them. New plants like to start out in rich and well drained soil, but not watered too much since they can be susceptible to rust and fusarium wilt.  

The white, pink, rosy pink, red, somewhat purplish or bicolored half inch wide flowers form rather flat dense trusses on top of short stems. Minute but abundant green bracts fill the spaces between the individual flowers. The rich green leaves below are about an inch to two and a half inches long. Mature plants of the more common varieties are typically less than a foot tall and wide. More compact and larger varieties are available as seed.