Bible Verses About Parables: Seed growing secretly

He said, “The Kingdom of God is as if a man should cast seed on the earth,

and should sleep and rise night and day, and the seed should spring up and grow, he doesn’t know how.

For the earth bears fruit: first the blade, then the ear, then the full grain in the ear.

But when the fruit is ripe, immediately he puts in the sickle, because the harvest has come.”