The outdoor pot experiments on the influence of weeds' growth stage and climate conditions on herbicides' effect were carried out in the Danish Institute of Agriculture Science in 2000-2001. The experiment concerning growth stage took into consideration three phases of Galium aparine: l, 2 and 3 whorls. The influence of temperature was performed using climate simulator running at three temperatures: 8/2°C, l 6.5/8°C, 24/16°C. The rain was applied using rain simulator 1, 3 and 6 hours after herbicides' treatment. Herbicides: Grody! 75 WG (amidosulfuron 750 g*kg-1), Aurora Super 61,5 WG (mecoprop 600 g=kg' + carfentrazone-ethyl 15 g*kt1), Lintur 70 WG (dicamba 65.9 g=kg', triasulfuron 4.1 g=kg') and Chwastox Trio 540 SL (dicamba 40 g*r1, MCPA 200 g"l', mecoprop 300 g*r') were applied in four doses: full recommended, 1/2, 1/4 and 1/8 of full dose on G. aparine. Grody! 75 WG and Aurora Super 61,5 WG were the most efficient to the youngest plants of G. aparine. Differences in susceptibility among three growth stages (1, 2, 3 whorls) to Grody! 75 WG were higher than to Aurora Super 61,5 WG. Effectiveness of tested herbicides tended to increase as temperature rose. The addition of adjuvant improved activity of herbicide Lintur 70 WG that showed satisfactory weed control even at four time reduced dose independently from temperature. The rain treatment 1, 3 and 6 hours after spraying caused reduction of Aurora Super 61,5 WG activity at 1/4 and 1/8 doses. The half dose gave a good result only when rain was applied 6 hours after treatment. Herbicide Grody! 75 WG was efficient after rain application (1, 3, 6 HAT) only at full dose.