Plant pots are no longer composed of a single material. Metal, wood, plastic, concrete, and various stoneware, such as pottery, are all common plant pot materials.
Each material has its unique qualities and will require distinct treatment. For example, you can fill a concrete or ceramic planter pot with dirt and grow a plant there. A flatwoven basket plant pot, on the other hand, will almost certainly require a plastic inner pot to prevent water from spilling out.