There are several types of stocks. The kind I was referring to above are virginian
http://www.butterflygarden.co.uk/butterflies/pages/gvw_c29n7.htm

I also love night scented stock
http://www.gardenandleisure.com/products/wsut122868.html

The plants are untidy but I don't mind that, and the scent in the evenings can't be beaten - I open my front door on summer evenings to a wall of scent I will definitely be planting some seeds this year.

I also usually buy some of these as plants. They also have a lovely scent. http://seeds.thompson-morgan.com/us/en/product/6507/2