Gardening With Allen: Mulches beneficial, vary in cost

Weed-barrier fabric mulch is the most effective in preventing light from reaching weed seeds. It also provides a physical barrier to weed growth, including perennial weeds. It is usually covered with some kind of granular mulch such as bark or rock. Weed seeds will blow in on top and sprout. However, they are shallow rooted and easily removed or sprayed. Weed-barrier fabric is usually limited to permanent plants such as trees and shrubs.

Black and colored polyethylene plastic can be used as a mulch for some larger vegetables such a tomato, pepper and squash. It should not be used for permanent plants because it does not allow enough air to reach deep roots.

Black and red lava rock, gravel and river rock are longer lasting mulches. They cost more to begin with but do not need replenishment very often.

I prefer organic mulches because they improve the soil as they are broken down by microorganisms. I use compost from my own pile. I use grass clippings around vegetables and fruits. I have also used newspaper to mulch vegetables. Both break down quickly and have to be added to frequently.

Bark is the most attractive and natural looking mulch to me. It is also one of the cheapest, especially if purchased in bulk. Bark comes in a range of sizes from large chunks to a fine material called bark dust. The chunk bark breaks down more slowly and needs less frequent replacement.

Chipped tree clippings are usually available free from arborists. Although not uniform in color or size of pieces they contain microorganisms that are very beneficial.