So often I ride around the area and can’t help but noticing the mulching done by people, both private and “professional.” A lot looks good, but almost as much looks horrible and is actually detrimental to the plants.
First things first; there are many types of mulch out there, i.e. pine needle, leaf, pine fine, cocoa, cypress, black and red, and the most common hardwood shredded. If you can get the hardwood double shredded you are better off to not have big chunks and strings of bark in your garden.
Secondly, regardless of what type you use the principle is the same. Mulch is to protect the plant roots from summer heat and dryness, and winter cold and freezing. It is best to do two applications a year in respect to the season. Application should not be more than 2-3” deep and definitely not against the woody trunk of the plant. Many times I see gobs of mulch heaped up around a tree trunk. What for? This could kill the tree with a nurturing zone for wood boring insects, rot, and development of a false root system.
Mulch should be spread evenly around the base of the tree, away from the trunk in a slight bowl shape. The effectiveness and purpose of the mulch is to protect the moisture feeding roots. It also looks good too, when done right. So don’t forget to break up or remove old mulch as it may be moldy (if heaped on too heavily) or compacted over time, and don’t overdo it.