The need to find effective alternatives to chemical herbicides increases with the progress of agricultural production. Bioherbicides have great potential for successful weed control in a more environmentally friendly way. Due to their specific properties, hydrosols attract the attention of many scientists who are exploring the possibilities of their application as bioherbicides. Hydrosols are relatively harmless to the environment and human health and cheap to produce. In this paper, a study was conducted to determine the effect of peppermint (Mentha x piperita L.), lavandin (Lavandula x intermedia), and mastic tree (Pistacia lentiscus L.) hydrosols on the germination of Perennial ryegrass (Lolium perenne L.) seeds. Germination of Perennial ryegrass seeds took place under laboratory conditions in Petri dishes containing filter paper soaked in undiluted and diluted (50:50) hydrosols. Seed germination rate under the influence of hydrosols was determined on the fifth and seventh day of the experiment by calculating the percentage of germinated seeds in samples. Undiluted and diluted hydrosols showed complete inhibition of Perennial ryegrass seed germination.