One of the most invasive species in Florida and other Gulf Coast States is Cogongrass. Cogongrass poses a major problem in natural habitats, on forested lands, rights-of-way and interstate highways. The present study was undertaken to evaluate the performance of cogongrass when grown in extracts of muhly grass (Muhlenbergia capillaries Lam) and chenopodium (Chenopodium ambriosiodes L). Genets and ramets of cogongrass were transplanted into magenta vessels containing 50% solution of root and shoot extracts of muhly grass and chenopodium, and placing magenta vessels in a growth chamber maintained at 28°C, 16/8 hour photoperiod and a relative humidity of 55 %. The genets and ramets of cogongrass were evaluated once per week for shoot and root growth, as well as rhizome extension after transplanting. Preliminary results show that the extracts of muhly grass and chenopodium reduced shoot growth and rhizome extension of cogongrass. Shoot extracts of muhly grass and chenopodium were more effective in reducing the performance of cogongrass compared to muhly grass and chenopodium root extracts. Root: shoot ratios of cogongrass also decreased by 50-70%. Thus, muhly grass and chenopodium extracts may contain some allelochemicals that could impact the invasiveness of cogongrass.