Each planter is polyresin, lightweight, fade resistant, weather resistant, environmentally friendly with a black finish. For indoor or outdoor use. The planters can be used in the winter it comes with drainage holes. You simply pop out the plug and the drainage hole is ready. With regard to winterization, we always recommend bringing the planter indoors. However, if they are placed in a covered area, with the drainage hole open and gravel at the bottom for drainage, it adds to the durability through the season. The key is to have the planter covered through the winter. If the planter is used in the winter for arrangements – it is recommended to use a pre planted arrangement in order to prevent the water from Pooling in the planter.