You can use cardboard instead of landscape fabric under gravel, but it will decompose within 1 to 2 years and stop blocking weeds. Cardboard works as a temporary barrier while you figure out a permanent plan. For gravel areas you want to keep for years, woven landscape fabric is the better long-term investment.
I laid cardboard under a gravel pathway along the side of my house three years ago. The first year looked perfect. No weeds, clean gravel surface, and the path drained well after rain. By the second summer, I noticed small weeds poking through in a few spots. When I scraped back the gravel to check, the cardboard had turned into brown mush in the areas that stayed wettest. The sections near a downspout had vanished almost completely. By year three, weeds grew through the path as if nothing was underneath it at all.
The reason cardboard fails under gravel comes down to what it's made of. Cardboard is cellulose fiber built to break down. Moisture from rain soaks through the gravel and keeps the cardboard wet against the soil. That constant dampness feeds bacteria and fungi that consume cellulose as a food source. The gravel sitting on top adds weight that compresses the softening material into a thin paste. Within two seasons, the once-rigid cardboard turns into scattered fibers mixed into the top layer of soil.
When you compare cardboard vs landscape fabric for gravel projects, the numbers tell a clear story. Woven polypropylene fabric holds up because microbes can't eat it. Engineers built it to hold up under stone for 40 to 50 or more years. Cardboard was never made for this job. It's meant to ship products to your door and then decompose in a compost bin.
Installing cardboard under gravel is straightforward if you decide it fits your timeline. Flatten boxes and remove all tape and staples. Lay them 2 to 3 layers thick with overlaps of at least 6 inches between sheets. Wet the cardboard with a hose so it molds to the ground surface. Spread 2 to 3 inches of gravel on top right away before wind lifts the edges.
Use cardboard under gravel only for paths you plan to change within 2 years. Test layouts and seasonal walkways are good fits for this approach. For permanent driveways, patios, and gravel beds, spend the money on woven fabric instead. You'll save yourself the weed battles and sinking gravel that come after cardboard dissolves. The upfront cost of quality fabric pays for itself within a few years.
Read the full article: Landscape Fabric: Pros, Cons, and Uses
