Phalaris arundinacea L. (reed canarygrass) is an aggressive graminoid species that invades wetlands in much of the northern United States. In areas previously used for agriculture and other recently disturbed habitats, P. arundinacea out-competes the native flora and creates monocultures, which reduce biodiversity and alter ecosystem functioning. Much research has focused on the growth response of P. arundinacea to varying abiotic and biotic conditions in the lab or under controlled field conditions, but few studies have examined if these results are congruent with what is observed in natural settings. We examined the relationship between P. arundinacea abundance and soil nutrient characteristics at Glacial Park, USA, a conservation area in northeastern Illinois. We found significant positive relationships between P. arundinacea abundance and total inorganic nitrogen, calcium and cation exchange capacity in the soil. These results are consistent with controlled experiments showing increased P. arundinacea growth in nitrogen-rich soil, and also suggest that calcium may influence P. arundinacea abundance in restored areas in the Midwest.