While the high firing temperature and quality of their glazed and terra cotta containers result in a durable and frost-resistant product, we still recommend that they are stored in a frost-free covered area in winter. If left outside, water may accumulate in the container and freeze, causing the planter to crack and break. Planters that must be left outside should be covered to prevent water, snow, and ice from accumulating inside the planter. This Smythe Terracotta Pot Planter glazed and terra cotta pottery is high-fired between 990 (terra cotta) and 1000 (glazed) degrees centigrade to ensure frost resistance and durability. Due to the processes used in the manufacturing of their hand-made and hand-glazed containers, all variations concerning firing, color, size, and crackling are natural occurrences in the manufacturing process. The glazes on their containers consist of natural, not chemical, components, and therefore the final color of the product will vary. This process creates the unique beauty of each piece.