Kenaf (Hibiscus cannabinus L.) is an annual fiber crop whose stems are a potential source of paper pulp. It can be grown under different climatic conditions resulting in a wide range of yield. Several studies in the southeastern USA have shown positive yield responses from higher plant populations. Effects of N on yield have been inconsistent. This study was conducted on a Hanford sandy loam soil (coarse‐loamy, mixed, non‐acid, thermic Typic Xerorthent) at California State University, Fresno, and was designed to investigate the effects of planting date (20 May, 20 June, 20 July 1981), row spacings (38 and 76 cm), plant population (86 450,172 900, and 345 800 plants/ha, 1980) and N (0, 45, 90, 135, and 180 kg N/ha, 1980‐1983) on the components of biological yield, basal stem diameter, and root growth of the cultivars, Tainung‐1 and a variation of Cuba‐2032. Total dry matter and stem yields were maximized at 345 800 plants/ha. Tainung‐1 resulted in higher stem yield than that of Cuba‐2032. Narrow row spacing (38 cm) resulted in higher yields than 76‐cm row spacing for both cultivars. Basal stem diameter was 2.3 cm for the lowest plant population and decreased to 1.63 cm for highest population. Cultivars and row spacings had no effect on stem diameter. Total dry matter yield was highest for the 20 May planting and decreased significantly with delayed plantings. Applied N at the rate of 135 and 180 kg/ha resulted in 71.0 and 83.5% increases in yield over the 0 kg N/ha rate. Nitrogen content in whole plants and leaf tissue increased, whereas the P and K content in whole plants decreased with an increase in applied N. Root growth increased with N rates up to 90 kg N/ha but was depressed at the 180 kg N/ha rate.