When you are ready to mulch, it is always a good idea to provide a new, deep edge around the tree, planting bed or walkway, so that the mulch is kept contained and does not fall out into your grass or walkway. Clean up any old mulch that has not decomposed so that the mulch does not get too thick. Once the area is cleaned up, you should apply a granular pre-emergent herbicide (such as Preen) to help with weed control. When buying mulch, try to use an organic mulch, such as bark, root or clean wood chips. These products will decompose and actually help the soil. A shredded mulch is ideal for sloped areas because it will hold and won’t wash out. When applying the mulch, make sure not to apply around the trunk of the plant or the root flare of the tree. You do not want the “volcano look”. This will reduce water and air to the tree and girdle the roots. You should only apply 2″ – 3″ thick, evenly over the entire surface.