Water conservation and environmental quality are of increasing concern to both greenhouse and nursery producers. The use of closed and semi-closed sub-irrigation systems, such as capillary mats, gullies and ebb and flow benches, to grow plants potted in organic growing media is an important step in this direction. Under extreme conditions, with such systems, salts can accumulate at the surface of the pots, possibly creating plant stresses. Salinity is associated with the activity of different chemical ions in solution, with different ions often moving at different rates through the columns. Thus the design of efficient sub-irrigation systems requires a detailed understanding of both the water and solute transport parameters, among other factors. A steady state solute transport (Br, K and Cu) experiment was carried out in the laboratory with three different growing media using solution samplers to determine the flux concentrations. The columns were then sliced into small sections at the completion of the experiment to obtain the resident concentrations. Two of the media containing a high proportion of sphagnum peat were found to have relatively constant water contents with height. However, the water content decreased significantly with height in the third medium containing a mixture of sedge peat and composted pine bark fines. Bromide and K were found to be relatively mobile in this substrate, with Cu being relatively immobile. The retardation of all three ions was considerably higher in the mixture of sedge peat and composted pine bark fines, due possibly to different soil solution-substrate interface interactions and to the capillary barrier effect. Solutions of the convective dispersion equation (CDE) gave reliable predictions of both the flux and resident concentrations. It adequately predicted the shape of the solute accumulation as well as the net displacement of salts toward the bottom of the pot if overhead irrigation was used.