Seed production of broadleaved birdsfoot trefoil, Lotus corniculatus L., is critical in southern latitudes to ensure the long‐term persistence of stands. Reproductive success of umbels produced early through late season was compared in a field test of 30 F1 genotypes grown on a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf) near Columbia, MO in 1984 and 1985. The F1 genotypes represented the progenies of three crosses among parental genotypes of PI 302921, ‘Norcen’, and ‘MO‐20’. All genotypes with 10 umbels, each with five flowers, were tagged at weekly intervals between 23 May and 5 July in 1984 and 1985, then harvested at pod maturity. Data were collected on number of pods produced per 10 umbels, number of viable seed per pod, mass of 100 seed, and number of days from tagging to pod maturity. Umbels produced at the early tagging dates produced more pods (P < 0.01), more seed per pod (P < 0.01), and had a greater 100‐seed mass (P < 0.01) than umbels produced at later dates. The responses noted appeared to be temperature related. Stand persistence is dependent on natural reseeding producing vigorous and competitive progeny. Management of stands to allow seed production from the early initiated flowers will promote better seed production and higher quality seed. The selection and development of populations with a shorter photoperiod requirement is indicated for growing areas below 40° N Lat to improve the initiation and development of flowers earlier in the season when seed production is better.