It depends on which type of wallfowers they are, the usual wallflowers you buy bare rooted are biennial so after flowering they die, but hardy perenial wallflowers are also available which will flower usually continually throughout
the year in a sheltered spot!

Thanks,I have decided to take more cuttings this year,as last years were so successful.They were originally the bare rooted ones,Dido,and lasted 3 years,so had my money's worth.