The main goal of our investigation was to determine the relationship between different growing methods of sweet corn seedlings and some physiological and morphological parameters of four hybrids in order to get information about the ability of their stress tolerance in a two-year experiment (2019, 2020). Seedlings were grown with and without pre-conditioning. Pre-conditioning is based on growing young plants exposing them to cold stress. Seedling emergence percentage, plant height, total leaf number, the total mass of fresh aboveground biomass, and ear length were determined as well as Soil Plant Analysis Development (SPAD) and Normalized Difference Vegetation Index (NDVI) values. In 2019, the pre-conditioned seedlings were more tolerant to cold stress for most of the tested parameters. Overall, the SPAD and NDVI values of the pre-conditioned seedlings were considered better in both years, however, it was not verified for all the studied hybrids. Among the hybrids, ‘Strongstar’ had the highest benefit from pre-conditioning compared to the standard growing method in terms of resulting in 17.5% higher plants, 13.1% longer ears, and 10.4% higher SPAD values in 2019. In 2020, when the cold stress was not so dominant, ‘Gyöngyhajnal’ gained the most from pre-conditioning with 9.7% higher plants, 32% more fresh aboveground biomass, 6.8% longer ears, 3.6% higher SPAD, and 9.3% higher NDVI values. More emphasis should be placed on the choice of stress-tolerant hybrids as well as on the seedling growing method and the date of transplanting to improve adaptation to the more frequent weather extremes.