Studies were conducted to evaluate the reportedly high yielding Mexican and European spring wheat (Triticum aestivum L.) cultivars under different management systems under southern Ontario conditions. We evaluated the potential of selections from spring wheat crosses and crosses between spring and winter wheat. Spring wheat yielded 20 to 32% less than spring barley (Hordeum vulgare L.) and 40% less than winter wheat in tests at five locations over a 4‐year period. Spring wheat lacked yield stability over years and locations. Tillering capacity, kernels per spike and kernel weight were lower in spring wheat than barley and winter wheat. The weakest component of spring wheat yield appeared to be the 20.6 average number of kernels per spike. A negative relationship was found between tillering and kernels per spike. This and the short period from seeding to maturity often associated with environmental stress may explain why management practices of increased nitrogen fertilization or reduced seeding rate had little influence on grain yield. Seeding delays reduced yields markedly. Spring wheat in southern Ontario appears to be limited by environment so that superior genotypes may not express their full potential. Crosses between spring and winter wheat lines may, therefore, have a greater potential for winter wheat improvement in Ontario than for selection of spring wheat types.