Answer: Torenia, also called wishbone flower, is grown as an annual in cold winter climates. It does well in a semi-shaded or dappled light location in a rich soil that is evenly moist yet well drained -- meaning not soggy. It will bloom from late spring or early summer through fall.
Exacum affine or Persian violet is typically considered a short term blooming gift plant or possibly a houseplant and so would not be your best choice for all season bloom in the garden and would certainly not be perennial.
If you are looking for blue flowers for summer color in the garden you might like the annual ageratums or possibly a blue salvia such as "Victoria" for a sunny location. Blue flowered perennials would include various campanulas, salvias such as "Blue Hill" and veronicas such as "Heavenly Blue" among others.
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