If your plants start out great but then die before they mature, I would suspect a watering problem. Is there a bottom in your planter? Maybe the planter can't drain properly and the soil at the bottom of the planter stays too wet. Have you dug down there to see what's going on?
What is your reason for using this planter as opposed to planting in the ground or in a standard planter box?
DaisyI said:Essentially, the roots are always sitting in water. You garden is drowning - that's the point I was trying to make.