Why use mulch in Chicago?
Mulch serves many purposes in your outdoor space. The primary purposes are to reduce water evaporation, prevent weeds, minimize erosion and add some beautiful texture to your outdoor space. Mulch will reduce the amount of water you have to provide your plants, especially in the warmer months. The mulch will reduce the number of weeds you get. Weeds will have a difficult time getting through a good 2-3 inch mulch spread. The amount of mulch used will vary by variety, so make sure you ask your local garden center (www.platthillnursery.com).
Mulch has been proven repeatedly to reduce the amount of soil runoff. To keep your beds intact, add thick layers of mulch to prevent the runoff of soil and keep your bed in place.
Mulch will give a much cleaner look than just plain dirt. There are several varieties of mulch that will give a nice aesthetic to your space.
Do I need to use landscape fabric or plastic under mulch?
Most likely you can skip adding plastic or landscape fabric under the mulch. If you are using organic mulch, the fabric will hinder the mixing of the material into the soil. Also, plastic can increase the water runoff which will hurt the plants long term.
Make sure you get mulch from a reliable source. For example, mulch could be stored next to a field with several different weeds and carry the weeds to your property. This could be an issue you have to deal with for a long time. Go to a reputable source like https://www.platthillnursery.com/bulk-products/
Bottom line, mulch is a great thing to add to your yard to minimize the maintenance you have to do and add great aesthetic value.