Many homeowners use landscape fabric (also called weed barrier) throughout their landscapes to minimize weeds. Landscape fabric restricts the light required for weed germination (since weeds seeds are in the soil), thus inhibiting the number of weeds that emerge. Research now indicates that the disadvantages of using these barriers outweigh their weed suppression qualities.
Although many homeowners may think using a weed barrier is a permanent solution to weed prevention, nothing could be further from the truth. Those rolls of spun polyester fibers or woven plastic strips may suppress weeds for a year or two, but they will eventually break down, especially if exposed to sunlight.
Ultimately, soil will blow on top of the fabric, where weed seeds may germinate. A weed’s roots can penetrate the fabric, making the weeds very difficult to pull. When removing the landscape fabric in order to pull the weeds, there is also a risk of disturbing the roots of other desirable plants in the vicinity.
Although landscape fabrics allow some air and water to permeate, the pores in the fabric can clog over time, further limiting the amount of air and water available to a plant’s roots. Plants may decline due to the limited amount of water and air available in the soil.
Because most homeowners cover landscape fabric with wood mulch (to create more aesthetically pleasing beds), the mulch sitting on top of the fabric is prevented from decomposing into the soil below (and thus, prevented from adding desirable organic matter to the soil).
In addition, healthy soil needs to have an exchange of carbon dioxide and oxygen between the soil and the atmosphere. When landscape fabric is used, the gas movement between the soil and atmosphere is one thousand times more restricted than when the soil is covered solely with wood mulch.
Weed barriers also have a negative impact on many of our native bees. Since many Colorado native bees nest in the ground, the presence of landscape fabric can impede their ability to tunnel underground.
Adding 3 to 4 inches of wood mulch to the bare ground around your plantings (after you have thoroughly weeded the area) is a great way to control weeds in your cultivated beds. The mulch will keep the soil underneath it moister and less compacted, which will make it easier to pull any weeds that do emerge. Since wood mulch will break down over time — adding organic matter to the soil as it decomposes — you may have to replace it every two or three years. Shredded leaves, pine needles, grass clippings, straw and pea gravel can also be used as mulch.
Using landscape fabric as a weed suppression tool has been shown to cause more problems than it solves. By foregoing the landscape fabric and just applying mulch at the correct depth to cover the soil between your plantings, you can reap the benefits of healthier plants and soil without increasing the amount of maintenance.
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