Turmeric (Curcuma longa) is one of the leading exported spice crop in Ethiopia. Weeds are a major constraint in Turmeric production. Understanding the critical period for weed competition and weed management techniques can be a tool for effective weed control and reducing the impacts of weeds. The experiment was conducted during 2012 to 2013 using randomized complete block design with three replications to determine the critical period and evaluation of weed management techniques. Timing of weed removal was based on the number of days after Turmeric planted. To determine critical time of weed competition, weeds allowed competing with Turmeric for 15, 30, 45, and 60 days after planting. In addition, season long weedy check and weed-free check were included as control. For weed management study five treatments were applied which contain both hand weeding and mulching at different periods. A total of 27 weed species were identified. The most important families according to the number of represented species were Poaceae (5 species), Compositae (3 species) and Amaranthaceae (3 species). There was a highly significant difference (p< 0.1) between treatments. When weeding was totally ignored yield loss amounted to 93.886% in 2012 and 90.55% in 2013 croping season. Number of tiller, number of leaf per tiller, plant height, leaf width and length, rhizome width and length, number of fingers per rhizome and yield were affected significantly at p< 0.001. Maximum yield loss were obtained when weeding applied at 60 days after planting which is 51.63% in 2012 and 34.69% in 2013, whereas, minimum yield loss were obtained when wedding applied at 15, 30 and 45 days after planting which was 11.63%, 21.467% and 27.119% in 2012, whereas 1.999%, 7.656% and 8.0926% in 2013 respectively. The result reviled that yield advantage of 45.264%, 38.408 and 33.63 in 2012 and 33.36%, 29.27% and 28.94% obtained when the first hand weeding was applied at 15, 30 and 45 days after planting when compared with the treatment where the first hand weeding was applied at 60 days after planting respectively. This result clearly indicates that sever crop weed competition has taken place between 30 and 60 days. Hence, it would be wise to apply the first hand weeding between 30 and 45 days after planting or weeding at 30, 60 plus mulching plus one hand weeding as needed were good agronomic practice help to avoid the period where sever competition takes place for maximum yield of the crop.