A Split-Split-Plot field investigation, with four replicates, in Complete Randomized Block Design, was performed to confront weed competition problems, in field grown tuberoses, under the Saudi Arabian Western Region Arid Zone environmental conditions. Integrated weed management practices, under different irrigation frequency regimes, yielded highly significant two and three way interactions, during the 2001/02 and 2002/03 growing seasons.                 Plots subjected to hand weeding every 4 or 8 weeks and irrigated every 8 days, exhibited noticeable reductions in weed population densities, fresh and dry weights, in comparison with unweeded controls and/or those weeded every 12 weeks.  Plots weeded frequently every 4 weeks and irrigated every 6 or 8 days revealed the lowest weed-water use efficiency, estimated on dry weight basis, when compared to unweeded controls and irrigated every 2 or 4 days.  Plots subjected to hand weeding every 4 weeks and irrigated every 8 days showed the highest weed control efficiency, in comparison with unweeded controls or those weeded every 12 weeks and irrigated every 8 days. Plots treated with glyphosate or pendimethalin plus glyphosate and watered every 2 or 4 days, immensely reduced weed density, fresh and dry weights, when compared to untreated controls or those treated with pendimethalin and irrigated every 2 or 4 days. Plots treated with pendimethalin alone or pendimethalin plus glyphosate and frequently watered every 6 or 8 days produced lower weed density, fresh and dry weights, than plots treated with glyphosate or lefted as untreated controls and irrigated every 6 or 8 days.   While glyphosate preferred functioning under wet moist conditions, Pendimethalin noticeably favored functioning on the drier side and stressful conditions.  Plots treated with Pendimethalin plus glyphosate, at all irrigation frequency levels considerably lowered weed-water use efficiencies, estimated on dry weight basis, when compared to those untreated controls at almost all levels of irrigation frequencies.  Plots treated with Pendimethalin plus glyphosate and irrigated either every 2 or every 4 days recorded the highest weed control efficiency, in comparison with the untreated controls.  Pendimethalin treatment alone under stressful conditions (irrigation every 8 days) exhibited appreciably high weed control efficiency performances, in comparison to its effects under high available moisture and irrigation every 2 days, in both seasons.                 Results indicated that, the most notable effects, for the highest weed population density, heaviest weed fresh and dry weights, were expressed by unweeded untouched untreated controls or untreated controls weeded every 12 weeks.  However, plots received Pendimethalin plus glyphosate and subjected to weeding every 4 or 8 weeks revealed noticeably contrasting effects.  The existence of Pendimethalin and glyphosate together in combination in one single treatment alone or along weeding every 4 or 8 weeks greatly increased weed control efficiency, when compared to other treatments.                 Unweeded controls or even those weeded every 12 weeks and treated with Pendimethalin herbicide or left untreated at all and irrigated frequently every 2 days noticeably encouraged emergence of high weed population densities and profusion, prosperous in fresh and dry weights. Whereas, unweeded controls receiving pendimethalin plus glyphosate or weeded every 4 or 8 weeks and treated with glyphosate alone or Pendimethalin plus glyphosate demonstrated the opposite performances.              Plots weeded every 4 or 8 weeks and treated with pendimethalin plus glyphosate at any level of irrigation exhibited the lowest water use efficiency, on dry weight basis.    Plots subjected to frequent hand weeding every 4 or 8 weeks and treated with pendimethalin plus glyphosate under 2, or 4 days of irrigation revealed the highest weed control efficiency, in comparison to plots lefted unweeded or weeded every 12 weeks and treated with pendimethalin.                 Tuberose cut flower yield was considerably influenced by the mutual interactive effects of the second and third order interactions; irrigation frequencies x hand weeding; irrigation frequencies x herbicides; manual hand weeding x herbicides and irrigation frequencies x hand weeding x herbicides.