I love these old fashioned flowers. They are easy to grow, give a wonderful show in mid summer and go on flowering for a long time (several weeks).
In Geoff Hamilton's lovely book 'Cottage Gardens', he describes the Sweet William like this:
'Dianthus barbatus - Sweet William
Height: 15-60 cms (6 in 2 ft)
Lovely old fashioned flower making a large head filled with individual florets like auriculas. However, flowering in mid-summer makes it an awkward customer, so it's now rarely grown, with the preference being for longer-flowering half-hardy bedding. If you can find room for at least a few, they're well worthwhile.'
Sweet Williams are bi-ennial so need to be planted now, as seeds, in order to have flowers next summer. I usually plant mine in a trough first and then, when the plantlets are big enough, I put them out into the garden to establish. The plantlets overwinter very well and grow steadily until they flower in June/July/August time.
I suppose they'll come back into fashion one day. I do hope so.
Millie being nosy.