Abstract: The objective was to determine the combined effect of seed sizes and seed cutting lengths on avocado seed germination behavior and seedling growth. The experimental treatments were a factorial combination of three seed sizes and three seed cut-lengths in a randomized complete block design with three replications. Cutting of avocado seeds hastened seedling emergence such that seeds with cut-length of 1.5 cm resulted in the earliest emergence of seedlings in 18 days. Medium seed with seed cut-length of 1.5 cm resulted in the shortest time to 50% germination whereas small-sized seed without seed cut delayed the period to 50% germination. Seedling height, leaf area and canopy size were controlled by similar factors along the growth path. In the early stages of seedling growth (WASG) variation in seedling height, leaf area and canopy size were determined by the seed cut-length. However, in the advanced stages of seedling growth (6 to 8 WASG), seed size was the determining factor in variation in seedling height, leaf area and canopy size. There were positive and highly significant correlations among leaf area and canopy size of seedlings (r = 0.87; p = 0.002), leaf area and seedling girth (r = 0.99; p = 0.000), canopy size and seedling girth (r = 0.99; p = 0.000) and number of leaves and seedling girth (r = 0.99; p = 0.000). The study concluded that mass propagation of avocado seedlings with assured uniformity was possible with medium to large-sized seeds with 1.5 cm cut-length at the distal end.