Just nine verses later there is an allegorical interpretation of the parable. In essence, it says that God is the farmer, the seed is the word of God, and the soil is people in different stages and conditions of their life. This interpretation, for one thing, suggests that the parable is an answer to a question the apostles must have been asking often by now. They had been traveling with Jesus for some time, and they were enormously impressed by him, but they noticed he wasn't gaining that large a following. Well, the word of God is sown, but sometimes it lands on a hard path.
Some people are just resistant, hardened to the faith.
They don't respond. Other people are like that thin soil over bedrock. The word of God takes root and starts to grow, but it doesn't last long because the roots can't get into the rock. Their faith flourishes, but it burns out. Still other people are like throwing the seed into a patch of weeds.