How to maintain large planters?

Dee,
I have 3 large planters that are set into my deck on the south side of my house. They get FULL SUN any recommendations of what to put in them. (besides Coleius. I have tried Petunia’s New Guinea impatents, marigolds, dahlettas, and none of them have made it even with good watering.
Sandy

Dear Sandy,
What wonderful conditions.  You really should try some tropicals in your planters.  If you have means to put a trellis in your planters the Madevilla or Dipladenia would be great in your planters.  They love lots of hot sun.   The sweet smelling Star Jasmine would be great on the deck as well.   If you are looking for something equally dramatic but not so tall you could try Hibiscus, another sun loving tropical.  Try Lantana and Cordyline and Geraniums (an old standard for a very good reason). Verbena loves heat and sun.  A Tea Rose surrounded with Alyssum and Verbena would be charming.   Tropical plants can add so much color and character to our intense, hot, and oh so short summers.  Give them a try.