Soils infested with weed seeds are considered hostile lands for crop production. In this context, great wild oat (Avena sp.) in winter seasons and redroot pigweed (Amaranthus sp.) in summer seasons represent problematic weeds in cropland fields. In a series of laboratory trials, we estimated the effects of gibberellic acid (GA3) and potassium nitrate (KNO3) on germination and seedling growth of Avena sterilis L. and Amaranthus retroflexus L. Different concentrations of GA3 and KNO3 were evaluated in randomized complete block design with four replicates. Findings revealed that GA3 at a rate of 200 mg L−1 along each of 150 and 250 mg L−1 treatment showed the maximum increases in germination percentage, radicle length, plumule length and seedling dry weight of A. sterilis L. All applied concentrations of KNO3 were similar (p ≥ 0.05) in enhancing seed germination of A. sterilis L. exceeding the control treatment. Application of GA3 at rates of 250, 500 and 750 mg L−1 surpassed the treatments of 0 and 1000 mg L−1 GA3 for activating A. retroflexus L. seeds germination. Addition of 250 and 500 mg L−1 KNO3 were the potent treatments for stimulating the radicle length of A. retroflexus L. It could be concluded that for breaking dormancy efficiently, addition of gibberellic acid or potassium nitrate with Avena sterilis L. as well as gibberellic acid with Amaranthus retroflexus L. is recommended. Such chemicals could be involved in weed management programs, since distinctive promotion of seed germination for the target weeds was achieved. This undoubtedly will keep the soil and crops healthy.