Answer: If you pick off faded blooms at their bases, you'll prolong the bloom period and you'll help tidy the plants up. Dianthus like full sunshine, and adequate moisture during the summer. Some dianthus are biennial and will die back after about 2 years. But all diathus self-sow so you've probably got plants of different ages, which would account for the non-uniform appearance. Go ahead and tidy them up after they've finished blooming.
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