[header] How to clean a garden sprayer [title] Finish on an empty tank. [step] Plan ahead with your herbicide or pesticide so that you're only filling the tank with as much of the liquid as you need. Spray plants a second time if you need to use up excess herbicide since almost all herbicides are approved to be sprayed twice. 
[title] Dispose of any liquid remaining in the sprayer. [step] Contact your local health department or environmental agency to find a safe way to dispose of this liquid.