The answer to 'why is my mulching' is that there are several common causes for issues with mulching, including using the wrong type of mulch, applying it incorrectly, or having soil or drainage problems. Symptoms may include the mulch breaking down too quickly, molding, or not providing the desired benefits like weed suppression and moisture retention.
To troubleshoot, first check that you are using an appropriate mulch type for your plants and climate. Organic mulches like wood chips, bark, or leaves work best. Apply a 2-4 inch layer around plants, but not touching the stems. Make sure the soil is well-draining and not compacted, as poor drainage can cause mulch to break down prematurely. If the mulch is molding or degrading quickly, you may need to refresh it more often or consider adjusting your application methods.