A new and distinct variety of Hibiscus syriacus, rose-of-sharon, named ‘;Whit XXI’;, particularly distinguished by having a compact, semi-dwarf, much branched upright elliptical shape, with dark green leaves, developing a high population of buds and flowers. Emergence of flower petals from the buds are at first dark red, then with expansion, red blotches on pink, then when fully opened the red blotches are no longer visible and flowers are pink. Flowers are sterile and long lasting.