Seedlings of carrot (Daucus carota L.) develop leaf necrosis when subjected to conditions which encourage rapid growth in controlled-environmental chambers. Necrosis occurred on the 4th and 9th developing leaves and was apparent as they unfolded. Injury was determined to be calcium-related, since foliar CaCl2 applications reduced injury and covering the plants during the dark period to promote translocation of Ca by root pressure flow stopped injury completely. Young unfolding leaves in covered plants had 50% greater Ca concentrations than those plants maintained in the chamber without covering. Carrot cultivars had different degrees of sensitivity to the leaf necrosis with ‘Red Core Chantenay’ > ‘Danvers’ > ‘Carousel’ > ‘Scarlet Nantes’.