The answer to 'when to mulching' is that the best time to apply mulch in your landscaping is in the spring and fall. In the spring, apply a 2-4 inch layer of mulch around your plants, trees, and shrubs to help retain soil moisture and suppress weeds as the growing season begins. In the fall, replenish the mulch layer to prepare your plants for the winter and insulate their roots.
Applying mulch at these times of year provides the most benefit for your landscaping. Mulch helps regulate soil temperature, retain moisture, and improve soil structure over time. It also gives your garden beds a neat, finished look. Be sure to keep mulch a few inches away from the base of plants to prevent rot or disease.