Buy seed from the farming shop.
Sow the seeds.
Sometimes your seeds are weak trash, and many would die before they germinate.
If necessary, move and replant the germinated seeds at the place you want it to grow.
Nourish with fertilizers.
It's fine if it dies, you can pretend that another plant is the protagonist all along and that the dead plant is actually a decoy.
At some point, you will get other farmers getting pissed at you for doing so well.
At some point, you will also get other farmers who belittle you and try to take your wife because he said you suck as a farmer.
You can let him take your wife or you can slap his face, telling him that his grandfather will teach him manners.
His family might retaliate, especially when you don't have a big or influential family.
But that's okay, because if they harm you, you can hit them with the law.
The law!
What is the law, you ask?
It is the law that I'm the protagonist, I'm always right.
So it's not fine for other farmers to slaughter your village, but it's perfectly fine if your protagonist does it.
It's even the moral thing to do for your protagonist to massacre the whole of his enemy's wheatfields whenever he feels like it, even when the other dude's slight is only that he accidentally stepped on the protagonist's toes.