Large lilac45blue flowers with a striking maroon centre smother this deciduous shrub from late summer through to october despite its tropical looks hibiscus syriacus 39oiseau bleu39 is fully hardy and provides a welcome splash of colour when many other plants have peaked great for sunny borders and requiring little maintenance this beautiful rose mallow has been awarded an rhs agm for its outstanding garden performance height 3m 40103941 spread 2m 40653941