Crop yield can be improved by minimizing plant-to-plant variability in seedling emergence. A study was conducted to determine the effect of variations in seed size and planting depth within a plot on emergence, proportion of infertile plants and grain yield in hard red spring wheat (Triticum aestivum L.). Large seed (40.8 mg kernel−1) was hand planted at 25-, 50- and 75-mm depths, creating three uniform seed size - planting depth treatments. Three other treatments consisted of repeating patterns within the same row: three large seeds and one small seed (23.4 mg kernel−1) at each of 25-, 50- and 75-mm depths. Two additional treatments consisted of 1) three seeds planted 25 mm deep and one seed planted 50 mm deep and 2) three seeds planted 25 mm deep and one seed planted 75 mm deep within the same row. Variation in seed size or planting depth within a row had no impact on percentage emergence, but nonuniform planting depth increased the proportion of infertile plants, mainly as a result of late-emerging plants. On a single-plant basis, mainstem grain yields were relatively uniform, but tiller grain yields were highly variable. When small and large seeds were planted 75 mm deep within a plot, the small-seeded plants produced 34% lower tiller grain yield than neighbouring large-seeded plants, while the large-seeded plants produced 10% higher tiller grain yield than plants from a treatment in which only large seeds were planted. Thus, the variation in seed size within a plot had no impact on total grain yield per plot. When seed was planted at variable depths within a plot, grain yield per plant produced by deep-seeded (75 mm) plants was only 20% of that produced by neighbouring shallow-seeded (25 mm) plants and was only 26% of that produced by plants where all seeds were planted deep (75 mm). Within-plot variation in planting depth increased the proportion of infertile plants (up to 158%) and decreased the grain yield. To maximize grain yield in hard red spring wheat, seed should be planted at uniform, shallow planting depth. Key words: Seed size, planting depth, emergence, fertile plants, interplant variation