The garden adage, "there's a plant for every pot" fails to address the issue of what pot to use. Both clay, or terracotta, and plastic containers provide good environments for plants to grow, but each also carries disadvantages. Luckily, plastic containers resemble other materials nowadays, avoiding the stigma of a garden filled with plastic.
Plastic containers in general cost considerably less than those made of clay. A properly maintained clay container will not need replacement nearly as quickly as a plastic counterpart. However, the quality and thickness of the plastic used affects costs and quality. Thin-walled plastic pots crush or break easier than higher quality, thick-wall plastics. Today complex resins constitute many "plastic" containers, and results in significant price increases since resins are stronger and weather better than ordinary plastics.
Both clay and plastic pots endure outdoor conditions well, but vary considerable in durability depending on the weathering element. Clay tolerates sunlight, wind, rain and fluctuating temperature changes above 32 degree Fahrenheit. The contractions and heaving of moist soils in clay pots leads to cracks and breakage when frosts and thaw happen outdoors. Plastic containers shed water and tolerate temperate changes perfectly, but ultraviolet rays in sunlight fades and weakens plastic over time. Plastic containers topple easily in wind, which may cause a crack. Also remember than plastic doesn't degrade once in a landfill.
Clay pots weight considerably more than plastic containers, but also adds to their strength. Tall plants easily catch the wind and put load stresses on the container base. Clay pots remain steadfast in breezes, while the lightweight plastic pots often weight less than the plants growing in them and often topple. From a maintenance perspective, plastic pots do not hurt your back or require a partner to lift and move.
Clay pots possess little flexibility; firm, thick and rigid describes them. No give occurs in the clay walls and base. Soils in clay pots naturally expand and contract based on moisture and temperature and cause cracks and section breaks during winter freezes and thaws. If a clay pot tips over, the weight of the soil and plants transfers entirely onto the stiff pot wall. Plastic pots remain flexible, although less so in cold weather and as they age. Breakage happens with plastic containers, but the pliability diminishes chances for full fractures.
Clay pots, made from natural materials, dry out quickly because of tiny pores throughout. Smooth plastic lacks pores and retains moisture better as air cannot penetrate through it. Clay pots provide superb growing conditions for plants that need fast-draining or dry soils, such as succulents or lavender.