When cotton (Gossypium hirsutum L.) is planted according to an "earliest planting date", exposure of the fully emerged seedlings to suboptimal temperatures is probable. Earlier, exposure to suboptimal temperatures from Day 4 through Day 10 post-imbibition was shown to inhibit both root and shoot growth in 10-day-old cotton seedlings. In this study, methods for preventing or lessening this inhibition were explored through applications of calcium (0.0, 0.1, 1.0, or 10.0 mM) to roots of two-day-old 31 C-grown seedlings of three cultivars ('Coker 315','Deltapine 61', and 'Paymaster 145') grown through Day 10 at 10, 15, 20, 25, 30 or 35 C. Significant interactions between calcium concentration and temperature and/or cultivar and between cultivar and temperature were observed in all growth parameters examined, i.e., root and shoot length and fresh and dry weights. Root and shoot responses differed, and treatment and cultivar effects on root:shoot ratios of those growth parameters were significant. Strong temperature effects on root and shoot relative water content were not prevented by exogenous calcium. Calcium was most likely to prevent or ameliorate temperature-induced growth inhibition at 20 or 25 C. Positive interactions between applied calcium and temperature stress indicate that exogenous calcium can serve to prevent or ameliorate suboptimal temperature stress in postemergent cotton seedlings.