Minecraft wiki entry for Crop_farming, associated text: Growth happens at random intervals and is affected by growing conditions. The average duration of each stage ranges from 5 minutes (in ideal conditions) to 35 minutes (in worst-case conditions). Aside from being placed on hydrated farmland, "ideal conditions" include having light sources (for night growth) and planting crops in alternate rows: each row of plants should be next to either a different crop or empty farmland. For the plants on the edges of the plot, it's also ideal to have more farmland beyond the row ends and the outer rows; however, this is rarely done since it amounts to leaving the edges of the available field empty. Full details of the growth mechanics are given below.