I seem to have a recurring problem with thyme. It settles in the first year, and spreads out nicely the second year. Then about the 3rd or sometimes 4th year, it starts dying out in the middle and looking scrappy. Does anyone else experience this? How can I prevent it? I really like to use thyme but find I have to keep replacing it.

what about if you trim it all back early spring, like you have to with creeping phlox, to refresh it? I don't know if it will work, but I had a Lithodora that was like that and I just hacked it back and WOW, all new green compact growth! Might be worth a try if you're going to have to replace it anyway.