I have a lot of old NoIDs that get no attention and no additional water than what Mother Nature provides. Even during our extreme heat and years of drought, these old toughies hung in there and bloomed. They are pretty bullet proof in my climate.
Some named cultivars that are pretty tough and seem bullet proof and/or are great growers:
Double Shot
Living On the Edge
Echo Location
Anxious
Total Recall
Honor Flight
Rainbow Shadows
Marching Band
Modern Drama
Thornbird (planted it in October, it bloomed and already has 8 increases)
I'm sure I could list more later.
I'd like to a list of irises that are hard to grow.
