I have self-watering plant beds, and I'm quite satisfied with them. However, I also make as much use of plastic plant bags as space permits, but they do seem to have one deficiency that I would like to eliminate, or at least reduce. That deficiency is the great disparity of moisture at the different levels. I've noticed that the bottom layer can be sopping wet even while the top layer is dry. I have a remedy in mind, but before I change my planting methods, I thought I'd check to see if anyone else has any experience with my proposed remedy. My proposed remedy is to use different soil mixes at the different layers so that the difference in drying out would not be so dramatic. There are other things I've thought of: wicks from top to bottom, ventilation shafts, etc.; however, altering the soil mix at different layers seems to be most promising. Incidentally, I have been using a mix of 1/3 peat moss, 1/3 vermiculite, and 1/3 garden soil, although I'm thinking of switching to ready-made potting soil to save time.