A field experiment was conducted at Punjab Agricultural University, Ludhiana during the summer season of 2014 to study the phenology and heat unit requirement of summer moongbean under different dates of sowing and irrigation schedules. Sowing on 20th March took increased number of calendar days (71.9 days) to harvest, while minimum (64.8 days) were noted under 30th March sowing. Among different sowing dates, the higher growing degree days (GDD), heliothermal units (HTU) and photothermal units (PTU) were reported under 10th April sowing at harvest stage (1258.0°C day, 13779.6°C day hour and 16908.3°C day hour). Sowing on 20th March recorded higher seed yield, biological yield, heat use efficiency (HUE) and photothermal use efficiency (PUE). Among different irrigation schedules, IW/CPE ratio of 1.2 recorded higher GDD, HTU and PTU (1280.5°C day, 13120.9°C day hour and 17274.1°C day hour). Seed yield and biological yield were also maximum under IW/CPE ratio of 1.2. HUE and PUE recorded non-significant differences under various irrigation schedules.