Answer: Columbine are short-lived perennials and usually need to be replaced every 3-4 years. If yours is a mild-summer climate, the plants will take full sun. Otherwise, they perform best with partial shade, especially from hot summer sunshine. Columbine will reseed if you allow the spent flowers to remain on the plants at the end of the season (though seedlings of hybrid plants may well show different growth characteristics and flower color than the parent). I'd guess that your plants have done all they're capable of doing and should be replaced this spring.
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