Some wildrice (Zizania palustris) commercial producers have observed that plants grown in deeper water develop larger seeds. Other effects of varying water depths on modern wildrice varieties have not been documented, including effects on rate and timing of plant development, and yield. Experiments were conducted in California and Minnesota to examine the influence of water depth upon rate of plant development, yield, and seed size of the wildrice cultivars Franklin and Petrowske Purple. Seedlings were transplanted into preflooded soils at a population of 190 m^-2in each of four replicated pots suspended at depths of 15, 30, 45, 60 and 76 cm in above ground tanks. In California, plants were grown in 11 L pails containing 12 kg of dudgen-graven pale brown loam which was amended with 11 g of 15-15-15 and 0.3 g ZnO and flooded one week before transplanting seedlings. In Minnesota, plants were grown in 11 L pots containing 9.3 kg of dry commercial topsoil (sandy loam). Two 6 g planting tablets (14-4-6) were inserted into each pot prior to flooding. A previously developed wildrice growth stage scale (WRGSS) was used to track development of plants grown at various depths. Seedlings were pre-germinated and planted at coleoptile emergence (03 on the WRGSS)--May 6 in California and May 9 in Minnesota. Observations of the growth stage at each depth were recorded every 2-4 days from planting until seeds were harvested. Temperature and light levels at the soil-water interface were recorded for each depth. Number of seeds per panicle was counted and seed weight (fresh and dried) was measured at harvest. Dried seeds were hulled and scanned for image analysis to determine differences in seed size, including length, width, and estimated volume.