Sheet mulching – benefit or barrier?

Alert reader Matt Wood pointed out a recent article in the NY Times on mulching with newspaper and wondered about my take on the topic.

For use on landscapes, I do not like sheet mulches of any stripe.  They tend to hinder to air and water movement, most especially in unmanaged landscapes like restoration sites.  A classic example is the use of cardboard or newspaper covered with wood chips.  The chips are easily dislodged, exposing the sheet mulch which quickly dries out and becomes hydrophobic.  Thus, the roots of desirable trees and shrubs lose out on the water, while the weeds surrounding the edges of the mulch benefit from the runoff:

Published research on sheet mulching in landscape settings confirms the drawbacks of sheet mulching.  But the article in the NY Times is about vegetable gardens.  This is a different situation – more akin to agricultural production than to landscape horticulture.  Vegetable gardens are routinely managed during planting, thinning, weeding, and harvesting.  Newspaper sheet mulches in these situations rarely dry out and, when kept buried and moist, do break down quickly.

So – keep the sheets on the (vegetable garden) bed where they belong!

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Linda Chalker-Scott

Dr. Linda Chalker-Scott has a Ph.D. in Horticulture from Oregon State University and is an ISA certified arborist and an ASCA consulting arborist. She is WSU’s Extension Urban Horticulturist and a Professor in the Department of Horticulture, and holds two affiliate associate professor positions at University of Washington. She conducts research in applied plant and soil sciences, publishing the results in scientific articles and university Extension fact sheets. Linda also is the award-winning author of five books: the horticultural myth-busting The Informed Gardener (2008) and The Informed Gardener Blooms Again (2010) from the University of Washington Press and Sustainable Landscapes and Gardens: Good Science – Practical Application (2009) from GFG Publishing, Inc., and How Plants Work: The Science Behind the Amazing Things Plants Do from Timber Press (2015). Her latest effort is an update of Art Kruckeberg’s Gardening with Native Plants of the Pacific Northwest from UW Press (2019). In 2018 Linda was featured in a video series – The Science of Gardening – produced by The Great Courses. She also is one of the Garden Professors – a group of academic colleagues who educate and entertain through their blog and Facebook pages. Linda’s contribution to gardeners was recognized in 2017 by the Association for Garden Communicators as the first recipient of their Cynthia Westcott Scientific Writing Award. "The Garden Professors" Facebook page - "The Garden Professors" Facebook group - Books:

19 thoughts on “Sheet mulching – benefit or barrier?”

  1. Several places in by yard were covered with poison ivy, honeysuckle, multiflora rose,etc. I cut the multiflora and undesirable saplings to the ground. I stomped down everything else sometimes added fall leaves, mulched with shingles of newspaper sections about 6 sheets thick and added two to three inches of wood mulch on top to weight down. Two years later I could plant in the soil and only had an occasional escape. Rarely would any newspaper remain. I mulched around desirable saplings. All survived. I did not water. Maybe if those planting the restoration projects were willing to wait before planting, the newspaper mulching would be more effective. I also use the newspaper mulch to establish new beds quickly on areas that I intend to raise the elevation of the soil. After mowing grass close to the ground, I shingle with newspaper and add six or more inches of topsoil and compost. Then plant. All plants have done well. For routine maintainence I mulch with leaves, grass, pine needles, etc. Newspaper is no longer desirable.

  2. Beth, I think the key to your success is the thickness of your mulch. Most people using newspaper don’t put on nearly as much. Six or more inches of top soil or compost may not even need the newspaper underneath.

  3. I agree, Deirdre. Beth, in research on using sheet and what I call “three dimensional” mulches, 3-D mulches were more effective in weed control. Looking at mulch depth, best results are found when 3-D mulches are maintained at a minimum of 2.5-3 inches (that’s maintained, not installed then ignored). Thick layers of chunky mulch are most effective. So my question to you would be – why even bother with the newspaper?

  4. Six years ago I sheeted and deep (4″) mulched out my home lawns (mostly quack grass and dandelion). It took me most of the summer and it soon became apparent that newspaper alone (perhaps because it was a very wet
    summer) would not stop quackgrass. The new shoots are like small nails and easily punch through even landscape cloth. I eventually won out, but it took two years and sheets of 1/8th inch plywood as a layer in the tough spots.

  5. Three to five inches of mulch will not kill poison ivy, honeysuckle, saplings, brambles, multiflora rose, but newspaper does. Dave is right that it will not stop quack grass. After the perennial weeds are killed, then I would not use newspaper. The quack grass(I worked on a patch tonight) I pull up using a ground hog to loosen the roots. Then I keep after the pieces that come back. Never ending.

        1. The link for the blackberry demo doesn’t seem to be active. Is there a pDF available somewhere. Im very eager to try this approach.

  6. What is missing here in this conversation is sheet mulching with cardboard and newspaper is also a food source for earthworms, who in their work provide significant aeration and fertilization of the soil column

  7. Mark, neither cardboard nor newspaper is a particularly valuable food item for earthworms. It’s pretty much straight cellulose. Recent studies have suggested the importance of high-quality food materials, such as seeds and seedlings, for earthworm nutrition. Moreover, without a well-aerated environment, earthworm activity will be lower than normal. There’s no denying that sheets of material are going to limit oxygen diffusion.

  8. I think it has to be done well. I sheet mulched a large area of my lawn to prepare it for perennial planting last season. This spring, I was able to plant right into it, no sign of grass. I used a good layer of carboard followed by sheep manure, topsoil, and compost, then mulched it well with fall leaves. When I dig in, the soil is moist and teaming with happy earthworms. Oh yes, and the plants are very happy. Point is, you can’t just slap down newspaper or cardboard and woodchips. On its own, this is too much carbon/cellulose. You need high nitrogen (manure), soil and nutritious mulch like compost and/or leaves.

    1. Tricia, it has little to do with carbon/nitrogen ratios and everything to do with water and gas transfer. Adding too much compost and other nutrient-rich materials can create nutrient imbalances and contaminating runoff.

  9. I’m wondering about the glue, printing ink, and any other chemicals in cardboard. If substantial amounts of cardboard were used for weed control in a garden, and that cardboard decomposes… Is there a residue that remains?

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