The Parable of the Growing Seed describes how the kingdom of God grows mysteriously like a planted seed. A man scatters seed which sprouts and grows on its own, without the man's help or understanding. This represents how God's Word can accomplish his purposes even without human intervention. When the grain is ripe, it is harvested, illustrating that God will bring forth the fruit of his Word at the proper time. The parable teaches that while believers sow the seed of God's Word, its growth in people's hearts is independent of human effort and belongs to God alone.