The answer to 'how often to lawn fertilization' is that most lawns should be fertilized 2-4 times per year. This helps maintain a healthy, green lawn by providing the necessary nutrients for grass growth and development. The optimal fertilization schedule will depend on your local climate, grass type, and other factors.
In general, it's recommended to fertilize cool-season grasses like fescue or bluegrass in the fall, and warm-season grasses like bermuda or zoysia in late spring or early summer. You may also want to do a light feeding in the early spring to give your lawn a boost as it emerges from winter dormancy.