I love the focus on the futility of human effort in these two parables. The grain grows "automatically" when the farmer sleeps. He told them the kingdom would grow undetected and appear to be doing nothing. And the farmer only contributes going to sleep.
Then Jesus goes to sleep himself. They did not see the connection and were terrified of the great storm. Then Jesus wakes and calms the storm and they are even more afraid of the great calm and the king who ruled the sea.