Minecraft wiki entry for Pumpkin_Seeds, associated text: Pumpkin seeds can be planted only on farmland. Over time, they grow into a stem and produce a pumpkin on any adjacent dirt, grass block, farmland, podzol or coarse dirt. If a pumpkin is already occupying an adjacent dirt/grass or farmland spot, the stem does not grow more pumpkins until the pumpkin is removed. A single stem can grow an unlimited number of pumpkins. Pumpkin stems need a minimum light level of 10 in the block above the stem to grow and give pumpkins. Pumpkin seeds are affected by bone meal only with respect to stem growth; bone meal does not help produce the actual pumpkins.