Mark 4:5-6

“And other fell on rocky ground where it did not have much earth, and it sprang up immediately because it had no depth of earth. And when the sun was risen it was scorched, and because it had no root it withered.”

Ancient ploughs could not plough up the ground like their modern equivalent. In comparison they but scratched the surface, and in many places there was little earth and the ground beneath was hard rock. The plough could do nothing about it. Thus there was nothing to give root to the seed. The result was that once there was a little rain it sprang up quickly, (all its energy went into quick growth), and it equally quickly died in the burning sun because it had no roots with which to draw on hidden supplies of water. This was a grief of heart to the farmer. The shoots showed so much promise and produced such little result. And the discerning ones among Jesus' listeners would remember the words of the prophets, ‘break up your fallow ground, do not sow among thorns' (Jeremiah 4:3), and ‘break up your fallow ground, for it is time to seek the Lord until He comes to rain righteousness on you' (Hosea 10:12), and would ensure that their hearts were not set like stone.