While it may not be their first choice, hummingbirds do like Foxglove (Digitalis purpurea), making it a great supplementary flower for a hummingbird garden. The fluted purple blooms grow on sturdy spires that can reach up to 5 ft. tall. Foxglove does best in consistently moist but well-draining soil. However, take care around children and pets because all parts of the plant are poisonous. Foxglove is hardy in Zones 4 – 8.