Four clones of sweet potato were planted in lsabela, Puerto Rico, each month in 1984, and after 4 months 6 measurements of yield were taken (number, weight/root, total weight of commercial sized roots, and total roots). Clones differed significantly with respect to all measurements, and significant differences were also found among months for all measurements. There were significant interactions between month and clone with respect to 4 of the 6 measurements. The 6 measurements were distributed over months bimodally for 2, and irregularly for 4 measurements. The measurements were not related to months by regression analysis. Differences among the 4 clones may be due to different responses to daylength, rainfall, temperature, and light intensity. It was concluded that sweet potato clones differ with respect to response to planting dates, and each clone merits separate evaluation.