Here are the pics

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By miclino at 2012-05-27

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By miclino at 2012-05-27

Sorry, I am slow to respond to your post. Your C. Australia appears fine to me. The lower primary leafs often die back. Hopefully by now the night temperatures have become more attractive to normal growth and you are seeing normal growth. As temperatures increase I think your red leaf color will become more pronounced.
If you suspect other problems, update with questions and photos. Kent

My "Australia" plants have been a consistent deep purple in leaf since they emerged in May, but maybe our early heat wave had something to do with it (we've had both abnormally cool and warmer than normal temps since then).

As to your watering, there's no way to tell what soil conditions are like under that mulch without checking.

You have them planted rather close. These are 6' plants. Check them at Horns at cannas.net.