Unlike the dahlias that are grown from tubers, the 'Happy Days' series of dahlias are compact mounds of foliage and flowers, topping out around a foot tall and wide. The serrated leaves are typically dark, some almost black, making the flowers pop. 'Happy Days Scarlet' dahlias produce large, single petaled flowers from late spring up until frost, and do well in sun-filled garden spots and container planters. This variety can serve as the summer color in year-round baskets or as the centerpiece for summer hanging baskets and planters.