This study evaluated the growth characteristics and forage productivity of quackgrass (Agropyron repens) and meadow foxtail (Alopecurus pratensis) as novel forage resources under abnormal climatic conditions in Cheonan, Chungcheongnam-do, South Korea, during the 2024–2025 growing seasons. Both species, sown on 26 September 2024, exhibited good establishment, vigorous pre-winter growth, and strong cold tolerance. Following harvest, quackgrass and meadow foxtail showed superior regrowth compared with orchardgrass and tall fescue. Dry matter yields of quackgrass (QG2), a mixed sward of meadow foxtail (50%) and quackgrass (50%), tall fescue and quackgrass (QG1) were 21.4, 20.4, 19.2 and 19.0 t ha⁻¹, respectively, with no significant differences among treatments. In contrast, the dry matter yield of meadow foxtail alone (18.4 t ha⁻¹) was significantly lower than that of quackgrass (QG2) (p<0.001). Crude protein contents of quackgrass and meadow foxtail (12.3% and 13.4%, respectively) were higher than that of tall fescue (11.9%), whereas total digestible nutrient contents ranged from 61.4% to 61.7%, slightly lower than those of tall fescue. These results suggest that quackgrass and meadow foxtail are promising forage species for mixed pasture systems to enhance adaptability to abnormal climatic conditions.