A new and distinct cultivar of winter-hardy, herbaceous, perennial, hybrid Hibiscus plant named ‘；Summer Carnival’； comprising an upright habit of multiple, well-branched, basal stems producing flowers near the top of the plant. Flowers are hot cerise, and the calyces display light green sepal centers and pale yellow margins while in bud and after flower drop. The foliage is primarily three-lobed, deeply incised, and grayish-green with creamy irregular margins frequently blushed with reddish purple. The stems exposed to high ultraviolet light develop reddish coloration.
