Be careful of the things we say and do. Because words and actions are the seeds, now they can be bad and negative words, which would not create a harvest but would fall to the ground among the rocks and thorns (meaning thatpeople really would not listen to what you had to say if it was always negative) But if yopu spoke live and words that built others up around you. It would create a harvest of others that did the same and that would grow the kingdom of God.

You have to lay the groundwork (create fertile soil) not just blindly throw Scriptures (scatter seeds) if you want to truly lead people to Christ (create a harvest).  My pastor was talking about this Sunday, not that specific passage but the fact that you have to truly love people and care for people and show them that, if you want to effectively witness to them.  Going up and shoving a tract in someone's face and telling them they need to come to Christ is rarely effective and true witnessing is a lot more than that.

@Mighty_Men_of_Valor - I am a little confused by your explanation, because verses 14,15 talk about how the seed is the gospel, not our words and actions.