Hhmm..
Interesting. I suppose the new hybrids can do just fine when grown in drier conditions, but I've never heard of being able to overwater moscheutus. Perhaps they're talking about growing them in conditions with poor drainage, but then again, marshy areas don't drain completely.
I do know my Texas Stars have adapted to much drier condtions in my garden. They get extra watering about once every 2 weeks.
So, basically, I don't know why they would say that either!
Barb

Hibiscus don't like "wet feet" or "dry shoulders". In other words, water when soil feels dry but do not allow to sit in saucer of water. Good drainage. This rule has always worked well for me.

In their native range (so this may not be true for all the cultivars) H.H. are found in marginal areas like wetlands and drainage areas. Pretty much the same conditions that would suit other marginal/bog species like Blue Flags or cattails, including being flooded or drying out from time to time...now once they are estabilished they can hold a good amount of water in their fleshy roots so they can adapt to drought contions. The newer ones may be different, but my southern bells and Blue River II's seem to tolerate pretty much anything, but grow faster when they have good amounts of water...