Some perennial plants that produce blue flowers include blue irises, blue lobelias, blue delphiniums, blue salvias and blue lupines. Other blue perennial flowering plants include blue rhododendrons, blue roses, blue thistles, blue lilies, blue aconitums, blue alliums and blue gentians.
Perennials are plants that live for several growing seasons, usually first blossoming during the summer or spring of the second year. The blue flowers of the "Rozanne" variant of the perennial geranium typically appear in June and wilt during the winter.
The grape hyacinth, which can grow up to 8 inches tall, also produces blue flowers. Other blue-flowering perennials include balloon flowers, blue anemones, blue orchids, blue tulips, blue veronicas, blue angels, blue forget-me-nots, blue columbines, blue poppies, blue cornflowers, blue daisies, blue chrysanthemums, blue hydrangeas and blue sea hollies.