Dianthus

Question

How much do I cut off of the old plant in the spring before new growth appears- leave it alone, or cut all the dead looking stuff off?

Answer 1

Cut the old growth back to about 1 to 2 inches in height.
If you did not do this in the fall, you can cut it back now.

https://www.gardeningknowhow.com/ornamental/flowers/dianthus/growing-dianthus-plants.htm