Seeds are packaged in many different types of containers. Since seeds are hygroscopic and can gain or lose moisture to the air, seed packaging must keep seeds as dry as possible. Larger quantities of seed are often sold in metal cans as shown here. Cans effectively protect seeds from rodents and moisture until they are opened. Cans should be provided with a resealable cap so that the unused seeds remain dry until used. Smaller quantities of seeds are often sold in foil or plastic packages. Packages that can be resealed after opening are preferred for vegetable seeds. Paper or cloth packaging should be avoided for vegetable seeds because they do not provide adequate protection from water.