Plastic does not have the wicking action that clay has making them an excellent choice for moisture-loving plants or for those gardeners who water infrequently. Plastic pots are made of inert materials and are considered safe for growing plants. Plastic pots generally have thinner walls than their clay counterparts offering roots little if any insulation from temperature change. Black plastic can actually act as a solar collector, heating up the potting medium to plant damaging levels. If plants in dark colored plastic containers wilt quickly, check to make sure the plants are well watered then move them to a shadier location where heat build-up should not be a problem.
Sunlight can be hard on plastic causing fading and brittleness.
Many plastic pots intended for outdoor use are treated with ultraviolet light inhibitors to reduce fading and maintain flexibility thus increasing the life-span of the pot. I hope you can use this information when choosing between clay and plastic pots at your favorite store. Whether it be plastic or clay, make sure the pot you select has drainage holes in the bottom to prevent over-watering. Iowa State University , Ames, Iowa. This information subject to a usage policy .