Cuticle cracking (also known as russeting, rain checking, or shrink cracking) can significantly reduce the quality of greenhouse-grown tomatoes, adversely affecting appearance and shelf-life. In this study, the effects of several environmental and cultural factors on cuticle cracking were assessed. Plants (`Trust') were grown at one of three nutrient feed concentrations, with electrical conductivities (ECs) of 0.7, 2.0, and 4.0. Higher EC initially reduced the amount of cuticle cracking. Over 14 weeks, the amount of cracking increased in all treatments and the differences due to EC became less evident. Over this same interval, 24-h average relative humidity (RH) gradually increased and was correlated with the increase in cracking. Further analysis showed that this relationship was due primarily to an increase in nighttime RH. No other climatic conditions were related to cracking. To test the possibility that the increasing age of the crop also could have contributed to the increased cracking over time, two crops of different ages grown in the same greenhouse were evaluated for cuticle cracking. The older crop consistently showed a greater amount of cracking than the younger crop. Our data suggest that EC is useful in controlling cuticle cracking under some conditions, but that nighttime RH or possibly some factor associated with crop maturity may override the effects of EC.