Think of mulch as a cozy blanket for your soil. The key word here is blanket, and thicker is better.

Think of mulch as a cozy blanket for your soil. The key word here is blanket, and thicker is better.

Mulch isn't something you sprinkle lightly on the top of your soil. Like a blanket, it's all about thickness. The idea is to smother weed seeds under a deep, dark cover so they can't germinate. The ideal thickness would be 2 to 3 inches of mulch laid on top of your native soil.

Mulch has benefits besides preventing weeds. It also can smother soil-borne funguses such as black spot, mildew and rust and prevent those spores from traveling up from your soil and onto your susceptible plants such as roses.

It is important to keep mulch 2 to 3 inches away from the crown of your plants — the area where the stem meets the soil. Too much mulch at the crown can cause crown rot by trapping moisture.

Mulch is not the same as topsoil, nor is it the same as a chemical pre-emergent product.

Mulch is made of lightweight, decomposed or composted green materials, while topsoil is dirt with mulch mixed in, and chemicals are chemicals.