Delphinium is the king of blues in the perennial garden. Tall, stately columns of spurred flowers open one by one from the bottom up, attracting domestic and wild bees, butterflies, and even hummingbirds. Flowers are pale sky blue to the deepest, most vivid blue of all flowers. Larkspur is an annual delphinium that imitates its perennial cousin in height and colour. Larkspur seed can be planted in the spring or fall.