Answer: Columbines usually produce flowers all summer long so I wouldn't cut the entire plant down. When individual flowers die you can cut away the flower, along with some of the stem. This way the plant won't direct energy into making seeds but will make more flowers. Then towards the end of the summer you can leave the flowers alone and they will set seeds. When the seedpod matures it will burst open and spread the seeds on the ground. Next spring the seeds will germinate and you'll have lots of new little plants. If you'd rather collect the seed pods instead of just letting them open and spill their seeds on the ground, cut the pods off the plant when they are mostly brown, but still have a little green at the top of the pod. At this point the seeds will be mature enough and you can cut the pod from the plant. Keep in mind that columbines tend to cross-pollinate so whatever color they were this year may not be the color the new plants produce next year.
Hope this anwers all your questions!
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