After recalling the concept of some most common soil feature, the differences in their use is remembered through examples. The hydrological properties of practical use, especially contrasting the open field conditions against the pot culture are examined with special attention to the upper water content (concept of field capacity, FC, and container capacity, Cc).The water retention curve is expressed according to the three most common concepts (as energy per unit mass of water, as hydraulic pressure head, as water pressure e.g. in kPa, once measured in bar). The transfer among these expression are given. The role of aeration in pot culture is pointed out. With special regard to pot irrigation there is the need to establish two thresholds, a “top-up” one and a” lower irrigation threshold”. When these are chosen a “generic composite index of the water regime” can be evaluated embracing both water parameters application, independently from the effect on the plant. On the other side the biological effects on plant grown might be more or less different on single plant trait or when dealing with different species. To this purpose one could estimate these effects calculating a “specific composite index of the water regime” evidencing the contributions of general culture conditions, or of single pot features and the irrigation regime.