Allotments 4 All

I have grown this from seed this spring and now have about six babies ready to plant outside . Anyone know how far apart I need to plant them for a great display ?  I believe they get very tall ,which is good ,  BUT  is this going to become a thug that I might regret !   

they have a 2m a 1 m spread so will need to take this into account http://www.cottage-gardens.net/ShowDetails.asp?id=149

Thanks that was just what I needed to know .   It is hard to believe that my tiny plants are going to grow so big !