Hello everyone! It's been a long while since I've been able to post, I am certainly in need of assistance.
I have a well established clump of Susan's approx. 4 ft. in diameter. The center of the clump is starting to get thin. I pulled up the clump in pieces and separated some plants out.
Reminds me of 'fairy ring' in hosta's. Are they known to develop a type of fairy ring? Can they become rootbound? The roots were incredibly tight. I have hardpan clay soil that is like concrete when it is dry.
I can't speak specifically about BES, but with many perennials, once the nutriants are depleted they decline but if they can produce side shoots the clump enlarges to get nutriants around it. In hard clay tho organic matter in the soil is used up and it gets hard in the middle. I get that here with older plants.
It only postpones dividing it if you use synthetic fertilizers because they contain salts that get concentrated in the soil.
I have heard of people just digging out the centers and replacing the soill there, but I tried that approach once but it was so hard to dig in my clay that I ended up dividing it anyway.
Another possibility is that an animal may have nested in it and killed the center. Most likly though, if it is an older clump, it just needs fresh loose soil with organic matter.
Never before have so few with so much promised to take away so much from so many and then laugh their asses off as the so many with so little vote for the so few with so much.
What I recently read in my new perennial book in this case is to dig out the center and add fresh compost to the middle of the "fairy ring". The fresh compost will encourage new growth and it should fill in. Alternately, you can dig it up and divide it and return part of the clump to the old spot and amend with some fresh soil or compost and spread the divisions around, share with friends, or otherwise get rid of them.