The heat resistance of vegetation at landfills is worth investigating for the determination of the optimal species for the biological reclamation phase. Insufficiency of experimental data on comparative stability of the stems and roots make it difficult to draw definitive conclusions about the heat resistance of the organs of the plants. It should be noted that many scientific works are devoted to the thermal stability of cultivated and agricultural plants. The reason is that the temperature conditions should be taken into account when growing vegetables, fruits and mushrooms. However, the heat resistance of weeds, specifically in landfills, has not been investigated thoroughly enough. Increased substrate temperatures at the landfill site, which are caused by the burning of waste, alter the microclimate, cause the greenhouse effect, and contribute to the climate change. The aim of the work was to investigate the heat resistance of 5 most common plant species that have evolved in the landfills of the Western Ukrainian Forest-Steppe District (Ukraine). The plant specimens were collected at the Lviv, Rava-Ruska and Chervonograd landfills. The heat resistance of landfill vegetation was determined according to the Matskov method during 2015–2018. The following materials, reagents and equipment were used for the experiments: green leaves of 5 species of the investigated plants (weeds) – wormwood (Artemisia vulgaris), absinthium (Artemisia absinthium), city goosefoot (Chenopodium urbicum), common burdock (Arctium lappa), dooryard plantain (Plantago major); 0.2 N hydrochloric acid; heated bath, thermometers, pipettes, petri dishes, crystallizers, electric hot plate, marker. The experiments were conducted in triplicate. During the investigation of the heat resistance of the landfill vegetation, it was found that the most stable species are wormwoods (Artemisia) in all areas of the landfill, and the least heat-resistant is city goosefoot. The temperature of 70–80°C is detrimental to all of the tested plants. It was found that the lowest heat resistance is characteristic of the plants that develop at the foot of landfills.