Although pistachio shells will decompose when you throw them out, you can keep them from ending up in a landfill by finding another use for them after you remove the nuts. The shells are pliable but strong, making them a durable material. In fact, scientists have even found a way to use discarded pistachio shells to reduce toxic mercury emissions produced by power plants.
Pistachio shells can keep plants and lawns healthy. Spreading crushed shells around a garden feeds the soil as the shells decompose, and their sharp edges, along with the salt remnants, keep snails and slugs away from plants. You can also put them at the bottom of flower pots to help with water drainage.
You can create musical shakers with pistachio shells and empty containers. Putting the shells in different containers produces different sounds: Tossing some in a tin coffee can will make much louder noise than shaking them inside a small plastic bottle. Kids and professional percussionists alike can use them.
Pistachio shells are a sturdy material for making crafts. Shells that are dyed red can be turned into a wreath for Valentine's Day decorating. You can tap small holes into the shells, paint them and string them together with other items to make jewellery. They can also be glued to objects, such as picture frames, lamps, gift boxes and mirrors, in a mosaic-style decoration.
When making potpourri, pistachio shells serve several purposes. They can be tossed into the mix to give it texture. They can be painted to match the rest of the blend's materials. They can also be used as a fixative (an ingredient that retains the potpourri's scent) by soaking the shells in an essential oil for a few hours, drying them and mixing them with the rest of the potpourri.