How Landscape Fabric Works

Landscape fabric is a textile designed to block weeds from sprouting while allowing air and water through to reach the soil below. The strategy seems simple: Put a barrier between the soil and a layer of mulch, and you will stifle unwanted plant growth, namely, weeds.

Initially, landscape fabric does work well. When first installed, it’s pretty effective at blocking sunlight, so weeds won't grow. The long-term impact of landscape fabric on your garden and its continued effectiveness are more complicated, though.

Landscape Fabric Downsides

Placing landscape fabric under mulch in garden beds can negatively impact your garden in several ways over time:

Landscape fabric doesn’t stop all weeds. Sure, it smothers the weed seeds already present. Landscape fabric doesn’t stop airborne weed seeds from landing in the mulch, germinating, and sending roots down into the fabric. These weeds are tougher to remove because their roots get enmeshed in the landscape fabric.

Landscape fabric harms soil health. One of the main reasons for using organic mulch like straw, leaves, or wood chips is that it decomposes over time and enriches the soil with nutrients. Landscape fabric creates a barrier that stops this natural cycle. Soil that is shrouded in landscape fabric does not get the much-needed recharge of nutrients and organic matter from decomposing mulch. This can lead to compacted, lifeless soil with scant populations of beneficial organisms like earthworms and microbes that are critical to healthy soil.

Landscape fabric gets clogged over time. While designed to be water- and air-permeable, pores in landscape fabric get plugged up with soil and debris over time, blocking the flow of air and water to plant roots. This leads to shallow root growth and stressed plants.

It’s difficult to add new plants and move existing ones. Once landscape fabric is in place, adding new plants to a bed or garden becomes cumbersome, requiring you to cut through the fabric to put in a new plant. You’ll also have holes in the fabric after plants die or you move or divide them.

Landscape fabric prevents plants from spreading naturally. Many perennials, including natives such as bee balm, black-eyed Susan, and coneflower, spread naturally over the years. Some annuals will reseed themselves, too. This won't happen if the soil is covered with landscape fabric, so you never get that beautiful evolution of plants growing and spreading on their own.

The Verdict

The consensus among most garden designers and horticulture pros is to skip landscape fabric in garden beds. Its long-term effect on soil health and its tendency to break down and become ineffective at suppressing weeds make it a poor choice in a bed where you want plants to thrive long-term. Landscape fabric is a good choice for use under hardscaping, like paths and patios, or any place where you do not want any vegetation to grow.

Alternatives to Landscape Fabric

Sheets of cardboard or newspaper. Place overlapping pieces of cardboard or newspaper under your mulch. They're biodegradable and an effective way to keep weeds down. As the paper and cardboard decompose, they add organic matter to the soil.

A thick layer of organic mulch. Put 4 or 5 inches of organic mulch on your garden soil to suppress weeds. This will block sunlight from reaching weed seeds and make it tough for them to germinate. The mulch will decompose and enrich the soil, contributing to the long-term health of your garden.