A compact herbaceous perennial to 60cm in height, with blue-green, lance-shaped leaves and large, balloon-like buds opening to wide cup-shaped violet-blue flowers 5cm across ...
Tall see-through perennials such as Verbena bonariensis can be set towards the front ... Some of the most popular hostas, such as ‘Halcyon’ and ‘Hadspen Blue’, are among those with the most dependable ...