Landscape fabric can suppress weeds, but only if you lay it correctly over existing growth
Yes, you can put landscape fabric over weeds, but the fabric will not kill them. What it does is block sunlight and prevent new seeds from sprouting. The weeds underneath will gradually die from lack of light over several weeks to a few months, depending on how established they are. The catch: fabric works best when you lay it on top of weeds that are already small or recently sprouted. If you're dealing with mature weeds with deep root systems, you'll have better results cutting them down first or pulling them out.
Landscape fabric is a woven or non-woven material that lets water and air through but blocks light. When laid flat against soil and weeds, it creates a barrier. Sunlight cannot reach the plants below, so they cannot photosynthesize. Without photosynthesis, they starve. This is different from a chemical herbicide, which actively poisons the plant. Fabric is passive—it just denies the plant what it needs to survive.
Key Takeaways
- Landscape fabric suppresses weeds by blocking sunlight, but does not kill them when ready; expect several weeks to months for buried weeds to die.
- Lay fabric directly on soil or low weeds, overlap seams by at least 6 inches, and anchor it with landscape staples or pins so it does not shift.
- Cutting tall weeds down to ground level before laying fabric speeds up the process and makes the fabric sit flatter.
- Fabric works best in garden beds and under mulch; it is less effective on slopes or in high-traffic areas where it shifts or tears.
- Landscape fabric does not prevent all weeds—seeds that land on top of the fabric or in mulch above it can still sprout.
How to lay fabric over existing weeds
Start by cutting down any tall weeds as close to the ground as you can. You do not need to pull them out by the roots—just remove the above-ground growth so the fabric lies flat. If weeds are very short or just sprouted, you can skip this step and lay fabric directly over them.
Unroll the fabric across the area and overlap the edges by at least 6 inches where two pieces meet. Weeds will find any gap, so overlapping is not optional. Once the fabric is in place, anchor it with landscape staples (U-shaped pins made for this purpose), landscape pins, or even rocks and logs. Staples should go through the fabric into the soil every 2 to 3 feet. Without anchoring, wind and foot traffic will shift the fabric, creating gaps where weeds can poke through.
If you are laying fabric in a garden bed where you plan to plant, cut an X through the fabric where each plant will go, fold back the flaps, and plant through the opening. Fold the flaps back over the soil around the plant base. This keeps the fabric in place while letting your plants grow.
Why fabric alone is not always enough
Landscape fabric stops light from reaching weeds below, but it does not stop seeds from landing on top of it. Windblown seeds, seeds in mulch, and seeds dropped by birds can all sprout in the layer of mulch or soil that sits on top of the fabric. For this reason, many people use fabric as a base layer and add 2 to 4 inches of mulch on top. The mulch adds another barrier and also makes the bed look finished.
Fabric also does not work well on slopes or in areas with heavy foot traffic. On a slope, water and gravity can shift the fabric downhill, and people walking on it can tear it or fold back the edges. In these spots, you may get better results with a combination of fabric and ground cover plants, or with mulch alone.
How long it takes for buried weeds to die
Small, recently sprouted weeds usually die within 2 to 4 weeks under fabric. Larger weeds with established root systems can take 2 to 3 months. Some perennial weeds—like dandelions or bindweed—may take even longer because they store energy in their roots and can push back harder against the darkness.
You will notice the weeds turning yellow or brown as they starve. Once they are clearly dead and no longer pushing against the fabric, you can leave the fabric in place permanently or remove it if you prefer. Many people leave it down because it continues to suppress new seeds.
Choosing the right type of landscape fabric
Landscape fabrics come in different weights and materials. Woven fabric is made from polypropylene threads woven together and is durable and long-lasting—typically 5 to 10 years or more. Non-woven fabric is made from fibers bonded together and is usually cheaper but breaks down faster, often lasting 2 to 5 years. Both let water through, which is important because you do not want water pooling on top.
Heavier fabrics (measured in ounces per square yard) last longer but cost more and are harder to cut and install. A 3 to 4 ounce fabric is a good middle ground for most home gardens. Avoid very thin fabrics—they tear easily and do not last long enough to be worth the effort.
When to remove fabric and when to leave it
If you laid fabric in a temporary area—like a path you plan to pave later, or a bed you will redesign—remove it once the weeds are dead and before you move on to the next phase. Leaving old, torn fabric in the ground creates a mess later.
If the fabric is in a permanent garden bed under mulch, you can leave it indefinitely. It will continue to suppress weeds and will not harm plants or soil. Over time, the fabric may break down (especially non-woven types), but by then the mulch layer and any plants you have grown will be doing much of the weed suppression work themselves.
Alternatives if fabric is not practical
If you have a very large area or steep slope, laying fabric may not be worth the time. Cardboard is a free alternative if you have boxes on hand—lay it down, overlap the edges, and cover it with mulch. It will break down over time, but it suppresses weeds for a season or two. Mulch alone (wood chips, bark, or straw) also suppresses weeds, though it does not work as well as fabric and mulch together. You will need to refresh mulch every year or two as it breaks down.
For small areas with just a few weeds, hand-pulling or digging is still the fastest solution. For large infestations, you might consider a sod cutter (a tool you can rent) to remove the top layer of soil and weeds all at once, then start fresh with fabric and mulch.
Frequently Asked Questions
Will landscape fabric kill weeds or just stop them from growing?
Fabric stops weeds from growing by blocking sunlight. The weeds underneath will gradually die from starvation, but this takes weeks or months depending on how established they are. Fabric does not actively kill weeds the way a herbicide does.
Can I put fabric directly on soil without cutting weeds first?
Yes, if the weeds are small or recently sprouted. Tall weeds will push against the fabric and create lumps, making it harder to anchor and less effective. Cutting them down first takes 10 minutes and makes the job much cleaner.
What happens to weeds that sprout on top of the fabric?
Seeds that land on top of the fabric can sprout in the mulch layer or in any soil that accumulates there. This is why adding 2 to 4 inches of mulch on top of the fabric is recommended—it adds another barrier and makes the bed look finished.
How long does landscape fabric last?
Woven fabric typically lasts 5 to 10 years or longer. Non-woven fabric usually lasts 2 to 5 years before it breaks down. Sunlight, foot traffic, and sharp objects all shorten its life. Covering it with mulch extends its lifespan.
Do I need to remove landscape fabric before planting shrubs or trees?
No. Cut an X through the fabric where the plant will go, fold back the flaps, plant through the opening, and fold the flaps back around the base. The fabric will stay in place and continue suppressing weeds around the plant.