Seeds of Urena lobata L. cv. 'Ex-Mokwa' and a local type termed 'Indigenous' were sown on 7 May at the start of the rainy season. The 'Ex-Mokwa' crop commenced flowering on 28 August and the 'Indigenous' crop on 6 November. Mature fruit was produced over 14 weeks by 'Ex-Mokwa' and 12 weeks by 'Indigenous', but the bulk of fruit production was confined to a six- to eight-week period commencing 6-8 weeks after the onset of flowering. Seeds maturing early or late within this period were of low viability. Significant viable seed production therefore occurred over a period of only 4-6 weeks. Greatest fruit yields with single harvests were obtained at the end of this period. Lower yields were obtained with later harvests owing to the shedding of fruit. The maximum yield of viable seed was obtained by hand-harvesting fruits at two-weekly intervals over a period of 16 weeks, commencing soon after the appearance of the first ripe fruit. The yield from a single harvest on the optimum date was 69% of this maximum yield. Two, three or four regularly spaced harvests did not significantly increase the yield obtained with this single harvest.