How Much Groundcover Bark Do I Use?

Types of Bark Mulch

• You can purchase bark mulch made from different types of trees. The most commonly found type is made of a combination hemlock and fir bark and is a rich dark brown in color. You may also find mulches in other colors, either natural or dyed. Cedar bark mulch is less attractive to insects than other woods.

  Mulch is also available in different sizes. Bark dust is a very fine grind, almost powdery, while large chunks can be 2 inches in diameter.

Normal Application of Mulch

• For most applications, mulch should be applied in a 2- to 4-inch thick layer. If you live in an especially dry climate, mulch may be applied in a slightly thicker layer, which allows it to retain more moisture.

  Depending upon the size of the bark pieces and the local climate, mulch may last one or more years. You can apply a periodic "freshening" layer to improve the appearance of existing mulch. This layer should be one inch thick. Mulch made up on larger chunks of bark will last longer than finer grinds.

Other Considerations

• Mulch can be a home to insects, fungi and even small rodents, especially if applied in a thick layer. Slugs and snails are destructive to plants, and thick layers of mulch, which is always moist, will attract these pests.

  If mulch is applied to thickly, roots from plants and shrubs can become embedded in the mulch rather than the underlying soil. This can be harmful to the plants, as the roots will be exposed or damaged as the mulch decays.

  Mulch can be effective in limiting the germination and growth or weeds. Thicker layers of mulch provide more weed protection, although some weeds will germinate no matter how thick the mulch.