`South Bay' lettuce transplants were grown in F392A styrofoam Speedling® flats at different levels of N to evaluate the effect of N on transplant quality and subsequent yield and head quality in the field. Plants were irrigated eight times over a 4-week growing period by floating flats for 30 min in nutrient solution containing eight 0, 15, 39, 45, or 60 mg·liter–1 N supplied from NH4NO3. Dry shoot mass, leaf area, and plant height increased linearly with increasing N rates and dry root mass and stem diameter increased in a quadratic fashion. Transplants with the greatest plant biomass were, therefore, produced with 60 mg·liter–1 N. Plants from the 15, 30, 45 and 60 mg·liter–1 N treatments were planted in sandy soil in plastic-mulched beds under drip irrigation. To optimize lettuce head maturity among the treatments, plants from the N treatments were harvest 53, 56, and 59 days after transplanting (DAT). The optimum time to harvest was determined to be 56 DAT. There was no yield response (measured in terms of head mass) or quality response (measured in terms of head height, head diameter, head compactness or core length) to N applied during transplant production. This indicated that transplants produced with 15 mg·liter–1 N gave equally good yield to those produced with 30, 45, or 60 mg·liter–1 N when N was applied via flotation irrigation.