Can Perennial Weeds Grow through Landscape Fabric?

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Willie writes on small engine repair, landscaping, and lawn care. He owned a professional lawn care business in Alabama for almost 10 years.

What Is Landscape Fabric?

Landscape fabric is a solid sheet of woven fibers featuring small perforations to allow water to soak through. They come in rolls 3ft (0.9 meters) wide and up to 300ft (91 meters) long (source).

Different brands take different design approaches. Some of them, such as the FLARMOR Pro Garden Landscape Fabric (link to Amazon), are made of polypropylene to withstand weathering.

The cost of the products varies based on the brand and level of thickness. You need to buy landscape pins separately to hold the fabrics in place. Most homeowners cover up the fabric in mulch so it can blend into the landscape.

Why Perennial Weeds Grow through Landscape Fabric

Perennial weeds grow through landscape fabric due to the following reasons:

Improperly Secured Weed Barrier

Plant growth and erosion expose an improperly secured weed barrier to the sun. With continued exposure, the material weakens. Strong perennials push through the barrier from under to reach the sunlight above the fabric.

As the perennials grow, they leave the landscape fabric more exposed and more prone to deterioration. Without replacing and securing the barriers correctly, the perennials will overrun the landscape, spreading across the fabric.

Your Wanted Perennials are Unhealthy

Flowering and fruiting perennials preferred in landscaping need a lot of nutrients to thrive. However, the impact of landscaping fabric on the soil structure means that they don’t get enough nutrients. They become weaker over time, dying off after a few years.

Perennial weeds are more resilient, so they often take advantage of the situation, spreading quickly and ultimately contributing to the demise of your desired plants.

Weed Is Growing Through the Holes

Growing a plant within the weed barrier requires you to make a hole in a part of the barrier. A few of these holes give perennials a perfect chance to spread across the topsoil. If the growing plant is a large species (shrubs), it will feel strangled by the original fabric hole, ultimately growing weaker.

If you don’t act quickly to give the plant more room, perennial weeds peeking through the hole already will hasten its demise and colonize the hole. Since perennial weeds grow wider and taller, they will continue to grow through the opening, damaging the fabric as they grow.

Why Gardeners Buy Landscape Fabric

As seen above, landscape fabrics don’t completely inhibit the growth of weeds across the garden, but they nonetheless remain popular. Some of their benefits include the following:

They keep most weeds from growing. Although some perennials can still push through landscape fabrics, the material is strong enough to inhibit the growth of other types of weeds. When the weed seedlings germinate under the fabric, most die due to lack of access to sunlight.
They remove the need for herbicides. If you’re a gardener with children or pets playing in the yard, you can’t try out all the chemical herbicides you can find off the shelf. Some of them are dangerous. Landscape fabrics can eliminate the need for these herbicides or at least reduce the frequency of use. (source)
They keep inorganic material off the soil. Mulches like shredded rubber have excellent aesthetic appeal when spread around the base of trees and shrubs. However, they don’t decompose. Landscape fabrics keep them from sinking into the soil, where they’ll do more harm to the ecosystem.
They can help with erosion control. Although most landscape fabrics can allow moisture to seep through, they protect the soil’s surface from sloped runoff, which can cause erosion.
They reduce evaporation. Landscape fabric over the soil can reduce the effect of sunlight and wind on the topsoil. Preventing evaporation keeps more moisture in the ground for your desired plants.

The Cons of Landscape Fabric

While there are some advantages to using landscape fabrics, some gardeners don’t like using them for the following reasons:

They keep out organic mulch. Pine needles, fallen leaves, rotting stems, and other organic mulch can’t replenish nutrients in the soil after biodegradation because the fabric functions as a barrier.
They prevent soil aeration. Earthworms are good for the garden because they aerate the soil (source). However, they need to reach the soil surface to survive. Landscape fabrics inhibit their movement, making the soil compact and unhealthy.
They prevent re-seeding. Landscape fabrics can hamper your results if your gardening relies heavily on desired plants spreading naturally through reseeding. The seeds can’t penetrate the fabric, so they can’t sprout. Organic mulch may allow initial growth, but new sprouts will die quickly.
Weed seeds may grow on the fabric. New seeds blowing onto the fabric can grow if you use organic mulch to cover the landscape fabric. The roots adhere tightly to the perforations on the surface, making it difficult to pull the weed without damage to the fabric.
They are expensive. Quality landscape fabric can withstand weathering. Some of them contain UV blockers. However, they are pricey and can significantly increase the cost of a landscape project.

Final Thoughts

Landscape fabrics are effective against most types of weeds. However, tough perennials can grow through them. If you’re considering using landscape fabrics to fight off encroaching weed, be sure to carefully analyze the pros and cons before your decision.

Consider how the fabrics can affect your garden flora and how they can affect the cost of gardening.

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