Landscape fabric when used as a weed barrier can cause more problems than it intends to solve

As a professional landscape contractor, I do a lot of remodels and renovation work. Often a homeowner inherits the mistakes the previous owner made including the use of landscape fabric or weed cloth. It may have been the advice of a misinformed maintenance worker or even insisted upon by the homeowner, but in any case there are several pros and cons involved. Being educated about this controversial issue is important for any homeowner considering an upgrade to their existing landscaping involving plants, gravel and irrigation systems.

The Pros – where fabric is useful

1) Prevents weeds from growing from underneath sand set pavers or synthetic grass

2) Reduces weed growth in rip rap lined drainage swales

3) Soil erosion control in difficult sites (where the fabric is also covered with gravel or rip rap)

4) Could be used as an alternative to using chemical based pre emergent herbicides . But this doesn’t really fix the issue of weeds as fabric only delays the need to control weeds until the layer of gravel collects enough debris and forms a soil in which weed seeds that are wind driven find a
place to germinate.

5) Suitable for a minimalist style landscape where mostly Cacti, Agaves and Yuccas are planted and where upgrades and changes are minimal.

The Cons – where fabric creates problems

1) The wrong type of material can deteriorate in UV sunlight. I’ve seen many gardens with exposed black plastic sheeting that over time, looks hideous.

2) Adding new trees and shrubs can be a real mess. Removing the gravel in order to dig the hole, cutting out the fabric is relatively easy, but finding the drip irrigation lines to provide new emitters may be a real headache.

3) Repairing a leak in the irrigation system. Since the drip lines are installed under the fabric, it’s often difficult to pinpoint where a leak is originating.

4) Weed prevention is temporary. Yes, fabric will prevent any weed seeds that are already in the soil from germinating, receiving sunlight in order to grow, but after a few years, enough debris will collect on top of the fabric and along with the gravel cover provide a good soil medium for wind driven seeds to collect and germinate. Clients must be educated that this will happen and be prepared to either remove weeds manually, use a weed killer or pre emergent herbicide.

5) Prevents perennials that reseed and bulbs from populating. Perennials that reseed like poppies and alyssum cannot spread and if that if your intent is to create a perennial garden that thrives and grows from year to year, fabric should not be used.

6) Can be a hazard when used on slopes with the wrong kind of gravel. When used on a sloped area of the yard where perhaps you have a pathway or frequently walk across, roundish types of gravel like crushed granite actually will slide across the fabric as you walk on it, enhancing the
likelihood of slipping and falling.

7) Prevents easy application of fertilizers. Since fabric is placed close to the root ball of the plant when initially planted, its hard to apply fertilizers to the “dripline” of the plant which is where the feeder roots are and continue to form a larger radius as the shrub or tree ages.

8) Prevents earthworms from improving soil structure. Earthworms need organic matter that forms on the soil surface and derives nutrition from the fungi and bacteria that grows on the organic matter. Earthworms also need access to the surface typically after soaking rains since they need a balance of the amount of moisture their skin is exposed to in order to breath.

Not all healthy soils require the presence of earthworms, but their existence does indicate a healthy soil.

Landscape fabric has its uses but is not always the way to go

We recently finished landscaping an entire vacant lot that will be used as an extended backyard from the owner’s main house. He wanted fabric over the whole area which was covered with gravel, shrubs and a waterfeature. It was about 11,000 square feet. Although I hate to use fabric, in this case the soil was so bad in terms of being almost like dust, we had to use fabric so the gravel would not simply disappear into the “soil”.