The current series of experiments was conducted to assess the allelopathic potential of fennel, rue, and sage seed and plant biomass on weed species hoary cress (Lepidium draba). The effect of plants was evaluated through: seed cogermination in Petri dishes, effect of water extracts from fresh and dry plant biomass in two concentrations (50 and 100 g l-1) in Petri dishes and pots, and effect of fresh and dry plant residues in rates of 10 and 20 g kg-1 of soil. The cogermination of seeds affected germination and seedling length of hoary cress with fennel seeds having the highest inhibitory effect and reducing germination up to 34.9%. The water extracts in Petri dish essay had various effects, however the dry plant biomass in higher concentration reduced germination and seedlings growth for up to 100%. The applications of the extracts from fresh biomass in pots with soil differed from results in Petri dishes. Sage extract in higher concentration inhibited germination for 34.2%, and fennel extract reduced root length for 22.7%. The effect of incorporation of plant residues depended on the plant species and amount of the plant residues and was both stimulatory and inhibitory. The emergence reduction was the highest with incorporation of fresh rue residues.