Sweet rocket bears aromatic clumps of soft lilac to purple flowers from may to july producing a stunning display when grown in large drifts despite hesperis matronalis being a biennial or relatively short45lived perennial it will easily seed about to form masses of blooms that will scent the air on a balmy summer evening the lavishly perfumed flowers will attract many pollinating insects making hesperis a superb choice for herbaceous borders and wildlife gardens sweet rocket is also exc