Using Cardboard in the Vegetable Garden

, written by Barbara Pleasant us flag

Brown marmorated stink bugs can be trapped using a cardboard box

Like most gardeners, I have my share of successes and failures. My most recent disaster occurred when a deer found my autumn carrots and plucked them out one by one while I slept. I put a ridiculous amount of effort into preparing that carrot bed, so now I need to cut my losses and preserve the bed’s ready-to-plant condition until spring. The best way to do this is to cover the bed with cardboard, held in place with stones, bricks, or pieces of firewood. In spring, I can lift the cardboard, give the bed a light raking, and put it to work.

Gardeners have different opinions on using cardboard in the vegetable garden, but certified organic growers can use what I call ‘clean’ cardboard – plain, unwaxed boxes with all tape and sticky labels removed, with minimal printing on the outside. According to the National Center for Appropriate Technology, “the basic components of corrugated cardboard seem to be relatively benign. Brown corrugated cardboard appears to be the least processed paper product. It therefore would have the lowest number and smallest quantity of chemical substances, compared to white, glossy, highly printed, waxed or otherwise coated cardboard, paperboard, and papers.”

“Cardboard
Weigh down cardboard with rocks to prevent it blowing away

Smothering Weeds with Cardboard Mulch

Besides, there are many ways to use cardboard in the vegetable garden that simply work. When I moved to my current garden ten years ago, a third of it had gone wild and grown into a tangle of nettles and blackberries, with a groundcover of poison ivy running through the whole mess. Working a section at a time, I cut back the invaders and covered the surface with several sheets of damp cardboard, with soil and pulled weeds between the layers to help maintain moisture. After a few months under cardboard, the wild things were weakened to the point where I could dig them out.

Using cardboard to create new gardening space is high on the list of recommended methods promoted by Wild Ones, a non-profit advocacy organization for native plants, because smothering surface vegetation with cardboard causes less trauma to a site compared to digging it up. Many gardeners build raised beds right on their lawns, and line the bottoms with cardboard to smother the grass – a technique that makes it possible to fill the beds and start gardening right away.

“Cat
Even the gardener’s helper enjoys a cardboard box!

A bit of advice: Shipping tape comes off easily when cardboard is wet, so I place boxes I plan to use in the garden outside and let them get rained on before I clean and flatten them. Cardboard mulch needs to stay moist, so plan to cover it with compost or another material if you live in a dry climate. Termites are occasionally seen in cardboard mulch that is kept too dry, so avoid using cardboard mulch in parched places close to your house.

Box Cloches and Bug Traps

In addition to using cardboard mulch to protect beds from compaction or subjugate weeds or grasses, this time of year I use box cloches around parsley and other marginally hardy plants. With the open flaps securely weighted, the box cloches block cold winds and extend the picking season by several weeks.

“Parsley
Protecting parsley with a cardboard box extends the harvesting season

Last autumn, I discovered by accident that a small cardboard box with more cardboard layers inside, placed near my deck door, made an effective passive trap for brown marmorated stink bugs (shown in the photo at the top of the page), which are determined to come inside for the winter in 44 American states and 4 Canadian provinces. They mistake the box for a safe haven, crawl inside, and are easily shaken into a bowl of soapy water on cool mornings.

The growth of e-commerce has increased the number of cardboard boxes coming into our homes, and at least some of that cardboard can be used in the garden. If you have ideas to share that have worked for you, please post them below.

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Comments

 
"My husband and I used cardboard in our garden one fall and it worked great for keeping weeds from growing as well as the ground from drying out. When we were ready to plant our spring seeds, we began the process of removing the cardboard and there underneath were two rattlesnakes. Fortunately, we heard their warnings before we lifted the cardboard they were under so we were prepared, but it was a good lesson in being aware of what can take up residence in our garden. Be sure to use a long handled rake to move the cardboard in case you encounter snakes and have a plan on what to do with venomous snakes should you find them in your garden. Lastly, be prepared should anyone get bitten - have numbers posted by the phone for emergency personnel and know your route to the nearest hospital. Read up on the types of venomous snakes in your area and be able to identify the type of snake encountered so the correct anti-venom can be administered."
Cathy on Friday 20 October 2017
"We had a large plot of land and it was very weedy. We put large pieces of cardboard from large appliances, 3 layers thick, over the area. The cardboard snuffed out all the weeds. We left it in place for years where we weren't planting and it can be lifted at any time for planting - no weeding necessary, soil is moist and loose (if you haven't walked on it). The cardboard composts over time which is great brown mulch for the garden. Be sure to use 3 layers and overlap them. Less than 3 will allow for weeds to grow. I think using cardboard is great! No problem with snakes here - just garter snakes which are harmless."
Steffany on Friday 20 October 2017
"Great to read posts from my gardners in arms from across the pond folks. Wow we don't have rattlesnakes to worry about here in the UK thank goodness so please take care over there. But many of us use cardboard for all the same reasons as yourselves and shredded paper on the strawberry patch helps keep them nice and clean from soil splatter in the rain. Best wishes for good growing seasons to you all."
Bill Elliott on Tuesday 9 January 2018
"I put cardboard through my paper shredder and use it as mulch. It works great for keeping weeds down, and moisture in. By the end of the growing season it has already started to break down and I simply turn it into the soil when I put the garden to bed for the winter."
Richard on Monday 26 March 2018
"Do you put soil on top of the cardboard or do you have to remove the cardboard after it has been there for a year or so?"
Lina on Sunday 22 July 2018
"I built a garden bed for vegetables and herbs this spring. First time garden bed. I laid 2 layers of cardboard in a 4 x 4 foot space, surrounded the space with cinder blocks, then build a wood frame atop the blocks. Placed 8"- 10" of drainage rocks over the cardboard and topped that with 10 cubic feet of soil. Getting a yucky slime fungus (or mold) in the bed, repeatedly. Used the same organic soil in some potted plants, no slime. Any ideas on why?"
Paticia Boglin on Thursday 4 July 2019
"we'd been using plain cardboard to smother weeds in our garden now for many years too Cathy (fully fenced and with netting to keep out chooks and possums). Many years ago I'd been working in our plot all day, with daily visits and went to remove a big area of cardboard and found 3 x snakes :) here in tasmania we have tiger snakes. They moved on calmly, and much slower than a far younger me haha! Having said that, I've never found any snakes living under cardboard with layers of mulch/compost on top. The garden's right next to a large dam and chook coop (mice, brown tree frogs = snake food). I've seen our free range turkeys kill whipsnakes. Thanks for memory."
gran Rose on Saturday 14 December 2019
"can i put cardboard down, then compost then top soil ad then plant my seeds?"
kim dack on Monday 23 March 2020
"@kim dack Sorry this reply is a bit late Absolutely you can, but I would advise soaking the cardboard first before laying the compost on top, this will weaken the cardboard and allow the roots of your crops to pierce through eventually, Over time the cardboard will breakdown it takes some time, but it will. This is the best and quickest method for staring a new bed."
Craig L on Sunday 31 May 2020
"Been putting cardboard and newspaper down for 12 years now. All my beds were made with layering moist cardboard or newspaper then compost then mulch. If I plant right away I will put garden soil over the compost, plant then put mulch around plants. Only problem I have had are ants so I use this pet friendly granules around the areas where they have been nesting. This year I made a front yard area using boxes, mulch then acting grow bags on top with my veggies. So far so good."
Catherine Madden on Wednesday 3 June 2020
"If I’m layering in vegetable garden boxes, should I put a layer of small rocks on top of the cardboard or below it? I’ll add my compost soil etc on top of those 2 layers"
Kathy on Sunday 7 February 2021
"I live in the desert within an alluvial fan valley where I'm trying to establish an edible garden for the food bank. Am planting a small Pomegrante grove and a Carob grove. My question is, is it safe to plant cardboard under plants if you won't be eating from them for 4-5 years ? It's mostly amazon boxes. I recently started planting Eucalypts, who seem to like this very well: lining the planting holes (native sandy soil) with a wet mixture of 1/2 cardboard and 1/2 peat moss, and fertilizer for a nitrogen source, top with about an inch of native soil then plant 5 gallon tree still in it's container but bottom removed. This encourages deep rooting and directed water to the pot so it sinks deeply. I will be planting tubs with asparagus also. Thanks"
Alexandra on Sunday 24 July 2022
"Alexandra, the only thing to watch for in a desert is creatures moving in because of available moisture. Glad to hear you are having good luck with cardboard, which is a little like half rotted leaves when used in sandy soil."
Barbara on Wednesday 24 August 2022
"for people just starting to garden. If you solarize your soil it will kill out a lot of your weeds. You can buy clear plastic from lowes or home depot and lay it on the wet dirt, sealing the edges with dirt to keep it in place. You don't have to try to do it all at once. A ten foot strip across your garden each summer can save a lot of weed pulling time. AND NO CHEMICALS !!"
Margaret I Moon on Sunday 14 May 2023
"Does using cardboard prevent bugs from coming upfrom the soil, likevine borers? "
Tanya on Friday 11 August 2023

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