Answer: The best way to keep your dianthus looking nice is to take a pair of scissors and cut the tops off, just below the lowest spent flower. Dianthus won't bloom a second time if they are not deadheaded because when the flowers fade the plant spends all of its energy making seeds. If you shear the tops of the plants off as the petals fade but before seed pods begin to develop, your plants will rebloom later in the summer.
Hope this answers all your quesitons.
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