Steve is right about the biennial nature of foxgloves. There are some cultivars however, that have been developed to bloom the first year(annual types), and some that are true perennials. What I've done is plant seeds near the blooming ones early in the season, which sprout and develop for the next year's bloom(first year growth is called a rosette). That way you can let the flowers of your blooming plants go to seed when they're done blooming, and that seed will germinate the following year when your rosettes from the previous year are in their second year and are blooming. Biennials are done after they go to seed and you can dispose of the plant. By the third year, you'll be digging 'em up and giving 'em away. The young rosettes readily transplant.
A word of caution about foxgloves(digitalis purpurea). They contain a powerful nerve toxin(digitalis), plus a couple more toxic substances. They are considered among the most poisonous plants in the landscape, so you may want to think about their placement in a public garden.
P.S. I just got back from sunny San Diego and I'm suffering(;-} ) from sensory overload! The desert( and EVERYTHING ELSE)is a riot of color and fragrance--youse guys out there are in Fantasyland by Midwest standards! Awesome...........
P.P.S. My crocus are starting to bloom!