Answer: 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. You can go ahead and tidy them up after they've finished blooming, or simply allow them to set seeds, which will spill onto the ground and become new plants. Eventually you'll have lots of blooms again as the plants renew themselves.
Q&A Library Searching Tips