Lining stops soil from washing into the ground below and keeps roots away from contaminated earth
A raised bed sits on top of existing soil, and without a barrier, water carries your garden soil down into the ground beneath while tree roots and weeds push up from below. Lining the bottom and sometimes the sides creates a separation layer. The material you choose depends on what you are growing, how long you want the bed to last, and whether you are concerned about chemicals leaching into your vegetables.
The most common approach is to line only the bottom with cardboard or landscape fabric, leaving the sides open. This stops roots and weeds from entering while letting water drain. If your raised bed sits on contaminated soil or you want maximum separation, you can line the sides as well — though this requires choosing materials that won't break down or leach toxins into the soil where your food grows.
Key Takeaways
- Cardboard is the cheapest bottom liner and breaks down in one to three years, which works well if you plan to refresh your bed regularly.
- Landscape fabric lasts five to ten years and lets water drain while blocking weeds, making it the most practical choice for most gardeners.
- Hardware cloth (metal mesh) stops burrowing rodents but must be paired with another liner to block weeds and soil loss.
- Plastic sheeting and treated wood liners can leach chemicals into soil and are best avoided for vegetable beds.
- Overlap your liner material by at least six inches at seams and extend it slightly up the sides to prevent soil from washing around the edges.
Cardboard: the cheapest option with a short lifespan
Cardboard breaks down in one to three years depending on moisture and soil contact. It is free or nearly free if you save boxes from deliveries, and it requires no tools to install — just lay it flat over the ground inside your raised bed frame.
Flatten the boxes completely and overlap the seams by at least six inches so weeds cannot push through the gaps. Wet the cardboard as you lay it down; this helps it conform to the ground and speeds decomposition. Avoid glossy or printed cardboard from produce boxes, which may contain wax or inks. Plain kraft boxes work best.
The downside is that cardboard softens quickly in wet climates and may need replacement after a single season. The upside is that as it breaks down, it adds organic matter to your soil. This makes cardboard ideal if you are willing to refresh your bed every few years and want to build soil health at the same time.
Landscape fabric: the middle ground for durability and drainage
Landscape fabric is a woven or nonwoven synthetic material that blocks weeds and soil loss while allowing water to drain through. It lasts five to ten years and costs between $0.10 and $0.30 per square foot, depending on weight and brand.
Lay the fabric flat over the ground, overlapping seams by at least six inches. find it with landscape staples or rocks along the edges so it does not shift as you add soil. The fabric should extend slightly up the inside of your raised bed frame — about two to three inches — to prevent soil from washing around the edges.
Landscape fabric works for most vegetable gardens and does not leach chemicals into the soil. It is durable enough that you will not need to replace it often, but it eventually tears from digging and root pressure. When it does, you can patch it with overlapping pieces secured with staples.
Hardware cloth for raised beds in rodent-prone areas
Hardware cloth is a galvanized steel mesh with half-inch or quarter-inch openings. It stops burrowing rodents — voles, moles, and gophers — from entering your bed from below. A quarter-inch mesh is more effective than half-inch but costs more and is harder to work with.
Hardware cloth alone does not stop weeds or prevent soil loss, so pair it with cardboard or landscape fabric on top. Lay the hardware cloth first, overlapping seams by at least six inches, then add your weed barrier over it. find both layers with landscape staples.
Hardware cloth is sharp and requires heavy gloves and careful handling. Wear cut-resistant gloves when unrolling and cutting it. If rodents are not a problem in your area, this layer is unnecessary and adds cost without benefit.
Materials to avoid in vegetable beds
Plastic sheeting — including black plastic and clear plastic — blocks water drainage and can trap moisture that leads to root rot and fungal disease. It also breaks down in sunlight and leaves microplastics in your soil. Do not use it for the bottom of a raised bed.
Treated wood liners (wood treated with copper compounds or other preservatives) can leach chemicals into soil over time, especially in wet conditions. If your raised bed frame is made of treated wood, line the interior sides with landscape fabric or plastic to create a barrier between the wood and your soil.
Rubber mulch and recycled tire material are sometimes suggested as liners, but they break down and leach compounds into soil. Avoid them in vegetable beds.
How to install a bottom liner step by step
Start by clearing the ground inside your raised bed frame of large rocks, sticks, and debris. You do not need to remove all grass or weeds — the liner will block them — but remove anything sharp that could puncture the material.
Lay your chosen liner material flat on the ground, starting at one corner. If using cardboard, flatten the boxes completely and overlap seams by at least six inches. If using landscape fabric, unroll it across the bed and overlap seams the same way. Wet cardboard as you go to help it settle and conform to the ground.
Extend the liner slightly up the inside edges of your frame — two to three inches — and find it with landscape staples spaced about 12 inches apart. This prevents soil from washing around the edges as you water. Trim excess material with a utility knife.
Once the liner is in place, add a layer of soil. The weight of the soil will hold the liner down and keep it from shifting. If you are using hardware cloth, install it first, then add your weed barrier on top before securing both together.
Lining the sides: when and how
Most gardeners line only the bottom of a raised bed. Lining the sides is necessary only if your raised bed sits on contaminated soil (lead, industrial pollutants) or if you want to prevent tree roots from growing into your bed.
If you choose to line the sides, use landscape fabric or plastic sheeting stapled to the interior of the frame. Do not use treated wood or materials that will break down quickly, as you want the barrier to last as long as the bed itself. Leave the top edge of the liner slightly above the soil level so it does not interfere with planting.
Lining the sides reduces drainage and can trap moisture against the frame, which accelerates wood rot. For most home gardens, a bottom liner alone is sufficient.
Frequently Asked Questions
Do I have to line my raised bed?
No, but lining prevents weeds from growing up into your bed and stops soil from washing into the ground below. If your raised bed sits on good soil and weeds are not a problem, you can skip lining. If weeds are thick or the ground is compacted clay, a liner saves work over time.
Can I use newspaper instead of cardboard?
Yes. Newspaper works the same way as cardboard — it blocks weeds and breaks down in one to three years. Use at least ten sheets overlapped by six inches. Wet it as you lay it down. Avoid glossy inserts and colored inks; plain newsprint is best.
How often do I need to replace the liner?
Cardboard and newspaper last one to three years. Landscape fabric lasts five to ten years. Hardware cloth lasts indefinitely if galvanized. You do not need to remove old liners when they break down — they become part of your soil. Replace them only when weeds start pushing through or soil begins washing away.
Will landscape fabric prevent all weeds?
Landscape fabric blocks most weeds, but some perennial weeds with strong roots can push through over time. It also does not stop seeds that land on top of your soil and sprout there. It is a barrier, not a complete solution — you will still pull occasional weeds.
Is it safe to use plastic sheeting in a vegetable garden?
Plastic sheeting is not recommended for vegetable beds. It blocks drainage, traps moisture, and breaks down into microplastics that remain in your soil. Landscape fabric is a better choice because it drains while still blocking weeds.