-Mulch is a gardener??s dream. Covering the soil keeps the moist longer so you have to spend less time and money watering in summer. Mulch also suppresses the growth of weeds so you need to kickback and enjoy your yard more. In hot summer areas, a blanket of mulch from the ground insulates the soil too helping keep roots cooler and plants happier and the layer of mulch from the soil helps prevent disease organisms that live in the ground from splashing up on plant leaves when it rains or when you water. If using natural mulch such as shredded wood or bark, composed, coco husk, pine needles or weed-free straw, the mulch will improve your soil as it slowly breaks down. There are 2 things to keep in mind when buying mulch. First, do not go too deep, keep your mulch between 2 and 3 inches. Pile too much up on the soil it could suffocate plant roots. The second thing to watch for in your mulch is to avoid spreading the mulch right up to plant stems. Leave a gap of a couple of inches between the plants and the mulch. This reduces issues of rats and also keeps rodents [unk] on to the mulch from [unk] on your plant stems. This guideline applies to all plants, trees and shrubs as well as perennials. Take the time to spread a couple of inches of mulch over your yard and enjoy the benefits.
SOURCE:http://www.bhg.com/gardening/yard/mulch/must-have-mulch/