We have a small balcony which we attempt to modify into a beautiful garden. On almost no monetary budget, we do what we can with salvaged castaways and various orphans; sometimes things look quite good. Our containers, we know, are invariably too small for the plants they contain. We have two rectangular plastic planters mounted on the balcony railing, and we have a number of big plastic pots on the balcony floor. At the moment, all of our plants are thriving, with clematis and fuschias growing by leaps and bounds. But surely there is a danger of their growing beyond the nutrient capacity of the soil in their containersâ€”or so I would think. So I've been dribbling in water solutions containing Schultz Plant Food 20-30-20. My inexpert theory is that it might be possible to thereby partly compensate for the plants having only limited space for their needs. This is all very unscientific. No measurements; only guesses. But I don't want to see the plants' present luxuriant growth suddenly "run out" of available nourishment and suddenly die back. Am I on the right track, or is my guessing quite wrong? Thank you.