Mature fine tailings and coke are waste products of the oil sands industry with potential for reclamation. A greenhouse study assessed whether substrates of various mixtures of mature fine tailings, tailings sand, peat mineral mix and coke would support germination, emergence and growth of three grass species commonly used in land reclamation. Select soil and vegetation parameters were monitored for 112 days in the greenhouse. Plant growth was inhibited in treatments with high proportions of mature fine tailings and coke compared to treatments with low proportions of mature fine tailings and coke. Agrostis scabra and Festuca saximontana were most affected by mature fine tailings and coke, while Elymus trachycaulus was most tolerant. Plant response varied with substrate and amendment. Plant growth was limited in unamended mature fine tailings relative to that in amended mature fine tailings. Plants survived in coke substrates, however, biomass, plant density, cover and health were low.