Aims: To investigate the effects of grape juice dilution and different temperature/nitrogen addition regimes on commercial-scale, high-density Shiraz and Chardonnay fermentations. Methods and Results: Duplicated fermentations (30 hl) were conducted at two temperatures for Shiraz and for Chardonnay. Two additional tanks of Chardonnay and Shiraz were diluted. Nitrogen was added once at inoculation or in aliquots over several days. Yeast concentration and viability was determined by flow cytometry. Fermentation chemistry was monitored by Fourier transform infrared spectroscopy. Fermentations arrested in both of the undiluted, higher temperature duplicate tanks of Shiraz. Different fermentation temperature resulted in sensorially different Shiraz, but not Chardonnay, wines made from undiluted musts. The converse was observed for wines made from diluted musts. Conclusions: High-density musts can be fermented completely using reduced fermentation temperature coupled with incremental nitrogen addition. Significance and Impact of the Study: This is the first study in duplicated, commercial-scale, high-density grape juice fermentations to address temperature, nitrogen addition, and juice dilution effects on stuck fermentation potential and wine sensory properties.