The recommended depth for most mulches is 2 to 2-1/2 inches; this application will address the primary objectives of weed control, water retention, and temperature stabilization. Mulches with large pieces, such as giant nuggets, will not cover as much area, due to their bulk. These mulch products are more suitable for decorative use, and should be used in conjunction with underlying landscape fabric.

The biggest mistake most homeowners make is applying mulch anywhere from 3 to 6 inches or more. This practice can lead to serious conditions for many landscape plants. A heavy layer of mulch drastically reduces the soil's ability to dry out, leading to soggy, water-logged soil around the roots of plants and shrubs. This condition is extremely damaging to azaleas, rhododendrons, most conifers, all taxus or yew, and many perennials.

Mulch piled up against a stem or trunk results in constantly wet bark--perfect conditions for disease development. Additionally, rodents may nest in this thick mulch and, during winter months when food is scarce, will feed on the softened wood.

Purchasing the correct amount of mulch for your situation will save you time and money. Garden centers stock mulch in bags containing enough material to cover 2 cubic feet or 3 cubic feet. To determine what coverage you'll need, multiply the width of your space by the length; this will give you the number of square feet to be covered.

• At a 2-inch depth, 2 cubic feet will cover 12 square feet
• At a 2-inch depth, 3 cubic feet will cover 18 square feet
• If you buy bulk, you'll need know that 1 cubic yard covers 162 square feet at a 2-inch depth.
• A small pickup will probably hold 1.5 cubic yards (coverage for 243 sq. ft.); a full-size pickup will hold at least 2.5 cubic yards (coverage for 405 sq. ft.).

Timing is Everything

Depending on where you live, when you spread the mulch determines the benefits. When the soil has warmed and begun to dry, it's time to plan how much you'll need. Don't mulch too early or the material will keep the soil from drying out. Plants begin root growth as sufficient oxygen becomes available and the soil temperature warms reasonably in the root area. If you live in a region where the temperatures stay cold, or the rainfall is heavy in early spring, put off mulching until May or June.

In areas where winter comes long and hard, apply a second application of mulch in the autumn, especially on new plants with shallow roots: shrubs and evergreens, herbaceous perennials, or strawberries. Water established plants thoroughly in late fall, then apply mulch. To reduce heaving on new or small plants, apply mulch immediately following the first hint of frost on the ground.

Mulch can be your best helper in the garden if you use the right material and follow accepted guidelines for use.