The message ink.net
from "SugarChile" contains these words:


With bark mulch, applied about two inches thick, I get good weed control and
erosion control. And the irises do just fine; they don't suffer from rot
and they bloom well. It works for me.

Have you thought of using grit or gravel? Most irises like a summer
baking and roots as dry as possible; gravel might provide thet better
than bark.

Janet.