I bought several of this plant in May and June. They are all healthy green but only one has produced flowers. But one reason I choose this plant is that it is advertised as being very much a perennial (unlike many other Dianthus).
In the spring of last year I started seeds for a mixed collection of Dianthus barbatus (Sweet William) in a large pot. They grew to several inches in height until they went dormant for the winter but never flower. With the coming of spring they started growing vigorously and the flower stalks reached over 18 inches in height, producing quite a display of flowers. The flowers set seeds which I harvested. After the Dianthus barbatus finished flowering about half of the plants died and the rest went back to being small plants of several inches in height. I suspect the survivors are perennials but will have to wait until next year to find out. I am planning to start some of the seeds I saved next week.
I would be very interested in your experience with Dianthus barbatus 'Heart Attack'. I suspect you will not see much action until next spring. Did the plant which did flower set seeds? If there are seeds, do you know if they will breed true?
Michael, I purchased 4 of these "Heart Attack" as healthy (albeit small) plants in 4.5" pots in May. One did grow to bloom quite well for several weeks but hasnt bloomed since. The other 3 have grown in width but with very little height and no flowers.
At this point I am just hoping they will establish enough to weather my winter.