Hibiscus Syriacus Big Hibiskiss The Hibiscus Syriacus Big Hibiskiss or Rose Mallow is a hardy deciduous shrub, which produces enormous exotic blooms all summer long. Perfect as a specimen focal point in a sunny border on as a container plant on the patio. Exotic and tropical, this is a must especially in a small garden where every plant counts. The sterile flowers can grow to 7inches across! Also know as Hibiscus ‘Walberton’s® Rose Moon’, this shrub can survive frosts and cold temperatures as low as -10C. Robust upright habit and attractive dark green foliage. Height: 3m (10’). Spread: 2m (6,6).