Yes, I understand that we are to guard our hearts because the issues of life flow from them. The seed parable does not say that God tends the ground, so it would be imporatnt to do as you did and see if other places using the metaphor say who does. And as you saw,we do the tending.Where are you folks getting this from? Jeremiah 4:3, and Hosea 10:12 say the following,
For thus saith the LORD to the men of Judah and Jerusalem, Break up your fallow ground, and sow not among thorns.
Sow to yourselves in righteousness, reap in mercy; break up your fallow ground: for it is time to seek the LORD, till he come and rain righteousness upon you. Hosea 10:12
Both of these verses say that WE are to prepare the soil of our hearts! It is WE who do the plowing.