Since the environmental conditions and cultural practices are unique in southwest Florida, a study was performed to determine the horticultural adaptability and performance of `Valencia' orange trees on four commercial rootstocks grown in a high-density planting. The trees were planted in 1991 on a flatwoods soil in a commercial grove at a density of 627 trees/ha. Leaf mineral concentration, growth, and fruit production and quality were measured 4 and 7 years after planting. Compared to Florida citrus leaf standards, leaf mineral concentration values were within the optimum to the high range. Yield efficiency expressed as kilograms of solids per cubed meter of canopy and juice quality in terms of juice content, soluble solids concentration, and kilograms of solids per box increased with tree age. Tree and fruit size were the highest for Volkamer lemon (Volk) and the lowest for Cleopatra mandarin (Cleo). Fruit yield was the highest for Volk. However, yield expressed in kilograms of solids per hectare was not significantly different between Volk and `Swingle' citrumelo (Swi) due to the higher solids per box for Swi. Yield efficiency was also higher for Swi than for Volk. Juice content and soluble solids in the fruit were higher for Swi and Cleo than for the lemon rootstocks. Financial analysis showed that at high-density planting, trees on Swi were the most profitable. On noncalcareous flatwoods soil, Swi is the best suited rootstock for high-density planting.