The answer to 'how often to mulch' is that most experts recommend applying a 2-4 inch layer of mulch around trees, shrubs, and garden beds 1-2 times per year. This helps retain moisture in the soil, suppress weeds, and insulate plant roots from temperature extremes.
Applying mulch in early spring and again in late fall is a common best practice. However, the ideal frequency may vary based on your climate, the type of mulch used, and the needs of your specific landscape. It's important to avoid piling mulch too deep around plants, as that can lead to disease and other issues.