I usually cut mine back about this time once the blooms fade...maybe to 6 or 8 inches tall. They put out new growth pretty quickly. Now if your stalks are limp or wilted, that's a different issue: maybe too little water or something.

Mine is perennial, dies out in late fall. I remove the dead stuff in the spring, and we start all over again with new and usually larger plant.

You're in the annuals forum, you know. You might pop over to the perennial forum and you'll see a bunch about napeta or catmint...

Good luck with yours!

excessive green growth can be a function of too much fert ... ken

My Walker's Low always flops open from the center. It is a common problem with catmint.

To prevent them from flopping, I bought those cheap 2 foot tall metal fences and just stuck them in the ground all around the plants. It works nice and my catmint stays up