The amount of 2,4-D herbicide needed per gallon of water depends on several factors, including the specific concentration of the product and the type of weeds you're trying to control. Always refer to the product label for the manufacturer's recommended mixing instructions. Generally, you'll find a range of ounces per gallon for different applications. Proper mixing ensures effective weed control while minimizing the risk of harm to desirable plants and the environment. Remember to always use personal protective equipment when handling herbicides.