Artificially constructed wetlands have been utilized for treatment of wastewater for decades. Originally designed for treating human wastewater, such wetlands have shown promise in other wastewater applications, including plant nursery and greenhouse (glasshouse) operations. Recently, these facilities have become more concerned about how to effectively minimize adverse environmental impacts associated with wastewater runoff from their operations. One solution is to utilize artificially constructed wetlands to reduce their impact. The authors investigated this problem by evaluating nitrate removal in water within three artificially constructed wetlands containing three treatments: 1) gravel alone; 2) gravel planted with vegetation; and 3) gravel mixed with spent mushroom compost and planted with vegetation. Nitrate removal differed among the three treatments, with mushroom compost-amended substrate showing greatest removal.