Waterlogged soil conditions during early spring can result in poor grapevine performance. In this study the effect of ridging as a method of soil preparation on the depth to the water table, soil air composition and vine reaction, as indicated by leaf water potential and stomatal resistance, was quantified. The soil and plant parameters were monitored throughout an entire growing season on 600-mm high ridges and flat control plots. Soil air analyses showed that under waterlogged conditions, oxygen in the soil air is to a large extent replaced by carbon dioxide. A linear relationship was found between oxygen and carbon dioxide concentrations, except during the phase of aeration directly following a period of continuous waterlogging. The production of ethylene, which is believed to be detrimental to vine growth, could not readily be traced under prevailing anoxic conditions. Ridging increased the depth to the water table, which resulted in higher oxygen and lower carbon dioxide concentrations in the soil air. Soil oxygen levels of below 16% may have resulted in the decrease in leaf water potential and increase in stomatal resistance noted for the control plots. These conditions of physiological stress prevailed until the water table dropped to a level below 600 mm. It is concluded that ridging, an alternative to deep soil preparation on waterlogged soils, produced a favourable environment for root growth on this marginal soil based on improved internal drainage and thus soil aeration.