And a harvest of righteousness is sown in peace by those who make peace. (ESV)
I am not a good farmer. In fact, while some have a green thumb, I like to say that I have a black thumb. While I am not a good farmer I do know a little about it. Very little. I know two basic principles that apply to what James is talking about in this verse. He is speaking of reaping a harvest of righteousness.
In order for us to have the proper harvest there are two things that I know for certain. If you want to reap a certain type of plant you must plant the right seed. The other thing I know is that if you do not care for what you have planted it will not yield what you want because weeds will also grow around it and choke it out.
Let's consider the seeds. It seems to be a no-brainer that you must plant the right seeds. The harvest that James is talking about is righteousness. Where many fail is that they think that their own righteousness will turn into God's righteousness. That is the wrong seed. If you do not receive God's righteousness as a gift you will never reap a harvest of true righteousness.
Secondly, let's consider the weeds that choke out a harvest. Jame actually described those weeds in the previous verses. He described them as bitter jealousy and selfish ambition (verse 14). You cannot allow these to grow with any attempt at harvesting righteousness. These things must be pulled out and destroyed.
We want to harvest righteousness. This happens by planting the right seed (salvation through Christ), and we need to get rid of jealousy and ambition. Let's be good farmers.