to plant: to set a vine, tree, or seedling into the ground so that it takes root and grows there.
This is the farmer's and the landowner's word for putting a plant where it will stay: pressing a vine slip, a young tree, or a seedling into prepared ground so that it roots and, after a few seasons, bears fruit. It is not the word for scattering seed across a field (σπείρω). Planting is slower, more deliberate, and aimed at something that will still be standing years later.
Most of its New Testament appearances are simply that. A landowner plants a vineyard, walls it, and leases it out. A fig tree stands planted in a vineyard, and its owner comes looking for fruit. In Lot's day people were planting and building right up to the morning the city fell, which is the point of the example: planting is what you do when you expect a long future.
Because planting is about taking root and lasting, it became a natural picture for what God does with people. Jesus says that every plant his heavenly Father did not plant will be pulled up by the roots, setting this verb beside the noun built from it (φυτεία) so that the plant and the planting are heard as one word.
Paul carries the picture into church work: he planted at Corinth, Apollos watered, and God gave the growth. He is not claiming credit. The whole force of the image is that the one who plants and the one who waters are nothing next to the God who makes anything grow at all.