Although the chemicals in fertilizers help your lawn grow green and flowers bloom profusely, they are considered a hazardous waste. Fertilizers contain high quantities of chemicals including nitrogen and phosphorous and sometimes pesticides or herbicides as well. If you can't use them up for some reason and have no one to give them to, proper disposal is the only remaining option. It isn't as simple as just mixing it in with your other trash.
Call your waste management or garbage removal company. Inquire about hazardous waste drop-off locations or pick-up services. If none are available, call your county or local university extension office to inquire if any known hazardous waste disposal programs are in your area.
Dispose of fertilizer in the trash if no hazardous waste services are available. Place granular fertilizer in a heavy-duty trash bag, then double bag it in a second trash bag and tie closed.
Leave liquid fertilizer in its container with the lid on. Wrap it in four or more layers of newspaper, so it is absorbed in the case of a spill. Place the wrapped container inside a sturdy trash bag and tie closed.
Place the bagged fertilizer inside your trash can with your regular trash on the day of trash pick-up. If taking your trash to a dump, notify the staff there is fertilizer in your trash.