If you’re thinking about adding a cottage-garden look and a vertical element to a planting bed, you may want to consider foxglove (Digitalis purpurea), which may extend up to 6 feet when in bloom, depending on the variety and growing conditions.
A biennial (it blooms the second year, then dies), foxglove nevertheless seems like an enduring perennial because it reseeds so readily that every year the dramatic flower spikes will appear in the garden. It prefers moist, well-drained soil and full sun to medium shade. Its blossoms — in purple, pink, yellow and white — attract hummingbirds. Please note that all parts of the plant are poisonous to people, pets and livestock. Foxglove is considered invasive along the West Coast and in some parts of New England.