Should you use landscape fabric under mulch? Short answer: no. Landscape fabric belongs under rock beds — gravel paths, decorative stone, river rock around a foundation. Under mulch, it creates more problems than it solves. Here’s the longer version, because most homeowners get sold on it every spring and deserve a straight answer.
What Is Landscape Fabric Actually Good For?
Landscape fabric does one thing well: it stops weeds from pushing up through rock beds. Under a gravel path, a decorative stone bed, or river rock around a foundation, it earns its keep. The rock holds the fabric down, nothing grows through, and you can go years without touching it. That’s the right use case for a weed barrier — and it’s a narrow one.
The fabric also keeps gravel from slowly sinking into the native soil over time, which is a practical benefit in our freeze-thaw climate here in upstate New York. Zone 5b winters are hard on ground-level installations — that extra physical separation layer matters under stone.
Should You Use Landscape Fabric Under Mulch?
No — and this is where the weed barrier under mulch myth costs homeowners real money. Every spring, the pitch sounds logical: lay fabric, spread mulch on top, done. No weeds. The reality plays out differently within a season or two.
“Fabric is not supposed to go under mulch. Fabric goes under rock. And the weed barrier usually only lasts five to seven years at maximum, so it really doesn’t do a whole lot.”
— Mitchell Roggenbuck, Roggenbuck Landscape & Design Co.
Here’s why the logic breaks down: mulch is organic. Shredded bark, wood chips, hardwood blends — they all decompose. That’s the point. As mulch breaks down, it deposits a thin layer of soil right on top of the fabric. Weed seeds blow in, land on that thin soil layer, and germinate perfectly well. Meanwhile, the fabric below is blocking water and air from reaching your actual plant roots.
You’ve paid for the fabric, paid for the mulch, and ended up with weeds anyway — plus a buried sheet of plastic that’s harder to remove than if you’d never put it down.
What Are the Problems With Weed Barrier Under Mulch?
The problems stack up quickly:
- Weeds grow on top, not through. Once decomposing mulch creates a thin soil layer above the fabric — which happens within one or two seasons — weed seeds have everything they need. The barrier stops working as a weed barrier.
- Plant roots are starved of oxygen and water. Healthy soil needs air and water movement. Landscape fabric disrupts both. The organic matter from your mulch — the nutrients that should enrich your beds — gets blocked from reaching the soil below.
- Removal becomes a project. After five or six years, roots from your own plants have grown into and through the fabric. When it degrades, you’re pulling shredded plastic from around established root systems. It’s a mess.
- It degrades regardless. Even a clean install with quality fabric breaks down over time. UV exposure, root punctures, freeze-thaw cycles — standard landscape fabric has a realistic lifespan of five to ten years in residential use, and the low-end stuff can start failing in two or three.
How Thick Should Mulch Be to Actually Suppress Weeds?
For a full breakdown of proper mulch depth, see our guide How Deep Should Mulch Be Around Trees and Shrubs.
What Actually Keeps Weeds Down in Mulch Beds?
Consistent maintenance, not a silver bullet. Here’s what works:
- A fresh thin coat of mulch each year. You don’t need to rebuild from scratch — adding an inch on top of existing mulch refreshes the light-blocking layer and knocks out seedlings that were starting to take hold. Annual topdressing keeps the system working.
- Clean edging lines. A properly installed metal edge creates a physical border that turf can’t creep across. It’s not glamorous, but it’s one of the most effective things you can do to reduce bed maintenance long-term. Without a clean edge, grass runners undercut everything.
- Pulling weeds while they’re small. A weed that’s been in the bed three weeks pulls out easily. One that’s been there three months has a root system. Early-season hand weeding for twenty minutes saves hours of work in August.
What If I Already Have Landscape Fabric Under My Mulch?
It depends on how old it is and what shape it’s in. If it was installed recently and your beds are looking okay, you might work around it for now — topdress with fresh mulch and manage the top-layer weeds as they appear. If it’s been in the ground five or more years, is shredding, or is visibly interfering with plant growth, pulling it is usually worth the one-time labor. We’ve done plenty of both — sometimes the right call is removal, sometimes it’s not worth the disruption to established roots.
If you’re in Ballston Lake, Clifton Park, Malta, or anywhere else we serve in southern Saratoga County and you’re not sure what you’ve got under your beds, we’re happy to take a look and give you a straight read on it.
Text Mitchell at (518) 419-9012 — he answers every one himself.
Text Mitchell a photo at (518) 419-9012 — he gives straight answers, no sales pitch.
