Cardboard vs Newspaper for Killing Weeds

For smothering weeds with sheet mulch, use cardboard when you want a tough, long-lasting barrier over a large area, and use newspaper when you need a thinner, faster-decomposing layer that conforms tightly around existing plants. Both work on the same principle: deprive weeds of light long enough and they exhaust their reserves and die. The differences come down to thickness, durability, how each handles water and air, and how quickly it disappears into the soil. Cardboard typically lasts a full season or longer and blocks light completely, which makes it the heavy hitter for converting lawn into beds. Newspaper breaks down in roughly two to four months, lays flat in tight spaces, and is gentler on soil airflow. Below is exactly how they differ, the trade-offs that matter, and which material to reach for in each common scenario.

Factor	Cardboard	Newspaper
Light blocking	Total; a single corrugated layer stops all light	Needs 6 to 10 sheets stacked to block light fully
Durability in soil	One full season to over a year	About two to four months
Best coverage speed	Fast over open ground; large sheets cover quickly	Slower; small sheets, more overlapping
Conforms around plants	Stiff; awkward around stems and curves	Flexible; molds tightly around existing plants
Water and air movement	Can slow infiltration if doubled or tripled up	Rarely impedes water or air once wet
Worm activity	Worms love the corrugation; strong feeding	Good, but less of a worm magnet
Prep work	Remove tape, staples, glossy labels; flatten boxes	Separate out glossy inserts; stack sheets
Best for	Killing lawn, new beds, paths, large reset jobs	Tight planting around existing plants, quick beds

Cardboard: The Heavy-Duty Light Barrier

Cardboard is the tool of choice when you want to kill an area decisively and not think about it again for a year. A single layer of plain corrugated cardboard blocks one hundred percent of light, which is the entire point of sheet mulching. Weeds and turfgrass underneath cannot photosynthesize, so they burn through their stored energy trying to push toward light they never reach, and within four to eight weeks most cool-season grasses and annual weeds are dead. Tough perennials such as Bermuda grass, quackgrass, and bindweed take longer and may need an overlapping double layer and a full growing season, but even these struggle to survive complete darkness combined with a thick mulch topping.

The corrugated structure is also a feature, not just a thickness. The fluted channels between the two paper faces give earthworms a humid, dark, food-rich environment, and worms congregate under cardboard in remarkable numbers. As they feed on the cardboard and the dying vegetation beneath it, they aerate the soil and pull organic matter down into it, leaving the ground noticeably looser and richer by the time the cardboard has rotted away. This is why no-dig and lasagna gardening methods lean so heavily on cardboard: it kills the sod while feeding the soil biology that replaces it.

Prep and laying technique

Use plain brown corrugated cardboard and strip off everything that will not rot: packing tape, plastic shipping labels, staples, and any glossy printed coatings. Heavily inked or waxed boxes (produce boxes are often waxed) resist breaking down and are best avoided. Flatten the boxes and lay them so seams overlap by at least four to six inches, because weeds find any gap and shoot straight through it. Soak the cardboard thoroughly as you go; dry cardboard sheds water and can wick moisture away from the soil, while saturated cardboard sits flat, conforms to the ground, and begins decomposing immediately. Finish with two to four inches of wood chips, compost, or other mulch to weigh it down, hide it, and hold moisture. If you are deciding between mulch types for that topping layer, our comparison of mulching materials for beds and paths covers which lasts longest over sheet mulch.

The one caution with cardboard is overdoing the thickness. A single corrugated layer breathes and lets water through once wet, but stacking three or four layers can create a slow-draining mat that perches water above it and limits oxygen to the soil below, especially in heavy clay or high-rainfall regions. For most weed-killing jobs a single overlapping layer is plenty; reserve doubling up for the most aggressive perennial weeds and keep an eye on drainage afterward.

Newspaper: The Flexible, Fast-Decomposing Option

Newspaper solves a different problem. Where cardboard is rigid and clumsy around obstacles, newspaper is thin and flexible, so it molds tightly around the crowns of existing perennials, hugs the base of shrubs, and tucks into the curves of an established border without leaving the gaps that weeds exploit. That makes it the better material when you are not clearing open ground but suppressing weeds in and among plants you want to keep. You simply lay sheets right up to each stem, leaving a small breathing collar, and the paper conforms to the soil surface where a stiff sheet of cardboard would tent up and leave light gaps.

Because a single sheet of newsprint is thin and porous, one layer does not block enough light to kill anything. The working layer is a stack of roughly six to ten sheets, which together stop light while still letting water soak through readily once wet. That thinner profile is also why newspaper rarely causes the air and water problems that thick cardboard can. It almost never perches water, and it breaks down quickly, typically vanishing into the soil within two to four months depending on moisture and temperature. That speed is an advantage when you plan to replant the same area within a season, and a drawback when you need a barrier that holds for a year.

What kind of paper is safe

Use the black-and-white newsprint pages. Modern newspaper ink in the United States is overwhelmingly soy- or water-based and breaks down harmlessly in the garden, so the old worry about toxic petroleum inks is largely outdated for plain newsprint. The pages to pull out are the glossy color inserts, ad circulars, and magazine-style sections, which use clay coatings and heavier colored inks that decompose poorly and are best kept out of food-growing beds. The same logic applies to office paper: plain paper is fine in moderation, but glossy, laminated, or heavily coated stock is not. For broader soil-building context around this, our overview of building healthy garden soil explains how paper mulches fit into a compost-and-mulch cycle.

How They Compare on the Decisions That Matter

On light blocking, cardboard wins on simplicity: one layer does the whole job, while newspaper demands a careful stack of six to ten sheets to reach the same darkness. On durability, cardboard again lasts far longer, holding a barrier for a season to well over a year, whereas newspaper is mostly gone in two to four months. That durability gap cuts both ways. For killing an entrenched lawn or a patch of perennial weeds, cardboard’s persistence is exactly what you want. For a quick weed knockdown in a bed you intend to replant soon, newspaper’s fast disappearance is the convenience.

On handling, newspaper is the clear winner for working around existing plants because it conforms; cardboard is faster for blanketing open ground because the sheets are large and you cover more square footage per piece. On soil air and water, newspaper is more forgiving, rarely impeding either, while thick cardboard can occasionally slow infiltration in wet, clay-heavy sites. On soil life, cardboard’s corrugation is a genuine worm magnet that supercharges decomposition, though both feed the soil as they rot. On sourcing and prep, both are essentially free, but cardboard takes more prep to strip tape and labels, while newspaper just needs the glossy inserts separated out.

Combining the two

You do not have to choose exclusively. A common and effective approach is to lay cardboard across the open expanses where you need maximum light blocking and durability, then switch to newspaper in the fiddly zones right around existing plants where flexibility matters. The two materials overlap and decompose together, and you get the best of each. In a lasagna or no-dig build, gardeners often run a base of cardboard over the lawn and use crumpled newspaper to fill awkward edges and seams before piling on compost and mulch. Whichever you use, the non-negotiables are the same: overlap the seams generously, soak it down, and top it with mulch.

Common Mistakes That Let Weeds Win

The most frequent failure is skimping on overlap. Weeds are relentless about finding light, and a one-inch gap at a seam becomes a line of survivors that march right through. Overlap every joint by four to six inches. The second mistake is laying the material dry. Dry cardboard and dry newspaper both repel water, shed rain off to the sides, and can leave the soil beneath bone dry while the surface looks mulched; soak everything as you lay it. The third is forgetting the mulch topping. Bare cardboard and newspaper degrade in sunlight, blow around, and look unsightly, so always cap them with two to four inches of wood chips, compost, straw, or leaf mold.

A subtler error is expecting either material to defeat the toughest perennial weeds in one pass. Bindweed, Bermuda grass, and quackgrass store deep energy reserves and can persist under a single layer for months. For these, use cardboard, double the overlap, extend the smothering through a full growing season, and be ready to spot-pull any survivors that find an edge. Finally, do not plant directly into the cardboard or newspaper before it has begun to break down unless you cut a planting hole through it and backfill with soil or compost so roots reach the ground below.

The Verdict

Both materials smother weeds effectively when laid right, and the better choice depends entirely on the job. Match the material to the situation and you will get a clean, weed-free bed with far less effort than digging.

Scenario: Converting lawn into a new garden bed. Use cardboard. Its total light blocking and season-long durability kill turfgrass decisively, and the corrugation pulls in worms that loosen and enrich the soil as the sod dies.

Scenario: Suppressing weeds around existing perennials and shrubs. Use newspaper. Its flexibility lets you tuck it right up to each plant’s crown without the light gaps a stiff cardboard sheet leaves around stems.

Scenario: Killing entrenched perennial weeds like Bermuda grass or bindweed. Use cardboard, double the overlap, and leave it for a full season. These weeds need the longest, most complete darkness you can give them.

Scenario: A quick weed knockdown in a bed you will replant this season. Use newspaper. It breaks down in two to four months, so it clears the way without leaving a barrier you have to dig out before planting.

Scenario: A large mixed project with open ground and planted areas. Use both: cardboard across the open expanses for durability and coverage speed, newspaper in the tight spots around plants for conformability. They decompose together into one cohesive layer.