The answer to 'mulching has weeds' is that mulch can sometimes attract and harbor weeds, especially if it is not properly installed or maintained. Mulching helps suppress weeds by blocking sunlight and preventing weed seeds from germinating, but it can also provide a fertile environment for existing weeds to take root and spread.
Common causes of weeds in mulch include using too thin a layer of mulch, not replenishing the mulch regularly, or allowing organic matter and soil to build up on top of the mulch. Symptoms include seeing weeds growing through the mulch or the mulch becoming compacted and matted. To solve this issue, you'll need to remove the existing weeds, apply a fresh layer of 2-4 inches of high-quality mulch, and maintain it by replenishing as needed.