Dead zone

Clumps that have grown too big don't flower as well, If your irises have grown into a circle with a dead zone in the middle, it's time to thin. Dig them out with a shovel. Discard roots that are damaged or dried up.

Type II rings have only a band of dark green turf, with or without mushrooms present in the band. Type III rings do not exhibit a dead zone or a dark green zone, but simply have a ring of mushrooms present.

The polluted runoff water that contributes to this "dead zone" comes from each of the 31 states between the Rocky and Appalachian mountain ranges that eventually drain into the gulf.