Planting yams inside sacks is a creative way to cultivate them in limited space or areas with poor soil conditions. Begin by filling the sack with a well-draining soil mixture. Then, cut holes in the sack for planting the yam tubers. Plant the yam tubers about 4-6 inches deep, ensuring they have enough space to grow. Water the yams regularly, and provide support as they grow. Harvest the yams once the leaves start to turn yellow and die back. This method can yield a good harvest of yams even in unconventional gardening spaces.