The effect on weeds and crop yield of a short-term polypropylene cover as a protection against carrot fly (Psila rosae) damage to organically grown carrots was assessed. Crops were hand-weeded prior to cover and then subjected to one of three weeding treatments during the covered period: none, one or two weedings. Total weed weight was greater with covered, versus non-covered, plots only for the one-weeding treatment. No-weeding treatments had the highest total weight of weeds, with no difference between one-or two-weedings, whether plots were covered or not. Three weeds were more frequent (as estimated by approximate cover) and taller under cover:Capsella bursa-pastoris, Hypochaeris radicataandPolygonum convolvulus.Covering the crop did not significantly increase carrot yield. Yield was lower for the no-weeding treatments, yet weeding more than once did not increase yield. Based on these and similar results, assessments are made on the weed response to short-term covering and the use of this cover by organic growers.