2,4-D is a popular herbicide used to control weeds in lawns and gardens. It is important to know how long to wait after spraying 2,4-D before fertilizing, as applying fertilizer too soon can cause injury to the plants. The general rule of thumb is to wait at least two weeks after spraying 2,4-D before applying any fertilizer. This will give the herbicide time to break down and be absorbed by the plants, minimizing the risk of injury.