Everything GardeningRotoplast & Self Watering Planter Systems

It needs to be able to thrive in a pot. The pot is about 7 inches deep or so. What i last had in there died (beans) from the heat. What is compatible with this kind of outdoor potting?

Even in my own garden, I saw that plastic sheets were placed just below a small layer of topsoil and mulch where some shrubs and flowers were being grown. What is this layer of plastic used for?
And if I wanted to suppress an invasive species (English Ivy) with this layer of plastic, would it work?