does cardboard keep weeds from growing

With luck, your garden is growing some lovely goodies right about now, whether you've planted for looks or for food. You may also be growing a few unwelcome weeds here and there as well. Sure, you can pull them up, but they always seem to come back, right? That's because their seeds are below the surface and they grow quickly. The solution? A simple piece of cardboard from an ordinary cardboard box.

As you can see from this video from the folks at Apartment Therapy , all you need is a piece of carboard—a side of a box will do, as long as it doesn't have ink on it or isn't coated in wax. Just put the cardboard down over the spots of your garden where the weeds are known to live, cover it over with a thick layer of mulch, and leave it alone. The cardboard will keep the weeds from growing up through the dirt and insulate the ground to a temperature that kills the weed seeds. Plus, the cardboard is biodegradable and should break down over the next year under the mulch.

Granted, this means that you now have a spot in your garden where you probably shouldn't plant anything new right now, so don't go laying down cardboard everywhere and try to grow something in the mulch on top right away. Try this in areas that you've cleared already, and leave the cardboard alone for a while. Apartment Therapy doesn't mention it specifically, but I've also heard newspaper works well for this purpose. Looking for some more weed-removal tips? We've got you covered . If you have any other garden-friendly weed-killing suggestions, make sure to let us know.

Does cardboard keep weeds from growing

Subterranean termites feed on the extensive network of roots from dead trees. They will follow the path of wood or moist soil in search of food. So your buildings need to be surrounded by a buffer, a barrier of dry, uninviting soil. Make sure your ground is properly graded, sloping away from the base of your structures. Gutters and downspouts should be moving rainwater away from the foundation so that it is kept dry.

USE A THICK LAYER: Some people mention using newspaper as an option. It’s a great way to manage weeds on your regular garden beds. To suppress a weedy or grassy patch, you would need multiple layers and a substantial mulch application placed on top. I prefer cardboard in landscape beds, using 2 layers (standard thickness). A single layer should work well if it’s extra thick.

Landscape or weed fabrics create an impassible barrier that stops the upwards growth of plants from underneath. So the soft stems and leaves get trapped beneath. When used in a home landscape though, an application of mulch is commonly placed on top. The mulch holds the fabric in place, blocks out the sunlight and further suppresses growth. Aesthetically, it looks nice. And as a short term solution for reclaiming a weedy bed, the fabric can help out.

It’s worth noting that cardboard is composed of cellulose. Thus, as with any other wood based product, it can serve as a food source for termites. If you have an issue with termites on your property then you might prefer to avoid making things worse by laying down cardboard. However, if this is the case, then there is more to do than simply avoid cardboard.


All the while the microbial processes that rejuvenate your soil are being hindered by this synthetic, barrier. Earthworms and various arthropods cannot freely pass from below the soil up to the surface.

THINGS TO AVOID: To reduce feeding sources for termites, it’s best to avoid all wood mulches and chips. That includes ones that might seem to be termite resistant like cypress or cedar. Eventually, the protective compounds in the wood will leach away and termites might feed on the wood particles.

Should you use landscape fabric? What causes it to fail? Are there any alternatives to a synthetic weed barrier? What should be considered as a long term solution?


HOW LONG DOES IT LAST? This process is a temporary solution, not a permanent fix. The big advantage to cardboard is that it doesn’t stay there forever, getting locked up in soil layers. I’ve seen the cardboard disintegrate after 6 months. But in other spots it’s still been there a year later.

CONSIDER THE SOURCE: In reality, termites serve a vital function in our ecosystems. Once a tree or woody shrub dies, termite colonies move in to break down the massive networks of buried roots. So if you are afraid of attracting termites to your property, then you might think twice about cutting down any trees or large shrubs on your lot. That is where the real termite invitation comes into play. A single medium tree will have deposited much more cellulose under ground than those few sheets of cardboard that you are contemplating.

According to Linda Chalker-Scott, Ph.D., of Washington State University, cardboard sheet mulches can be detrimental to a garden, particularly if they are not appropriately maintained. They can become havens for pests, including termites and voles, who often like to nest underneath them. They can become dislodged by wind or promote the disappearance of oxygen if the soil doesn’t drain well.

When using cardboard to kill weeds and grass in a new planting area, start a few months or an entire season ahead of the time you intend to plant. Heifer International suggests removing any tape or labels from the cardboard packaging before breaking it down flat. Use plain cardboard, as printer ink can be toxic. After placing the cardboard in your garden, anchor it down with rocks or bricks. Then, hose it down with water to promote gas exchange to feed the soil’s microbes.

Weeds are a common problem in most yards and gardens. If you don’t want to use harsh chemicals, one easy, practical and safe way to get rid of them is to use cardboard as a weed barrier. Cardboard sheet mulches can stop the upward growth of unwanted weeds. Still, you must carefully maintain a mulch made with cardboard, as it could promote a buildup of chemicals and bacteria and attract other unwanted pests.

You can further improve the soil’s fertility by layering organic matter, such as compost, leaves, grass clippings or straw, over the cardboard about 6 inches deep, according to the California Native Plant Society. Over time and with the help of microbes and earthworms, the cardboard will begin to break down. If some cardboard is still in place when you’re ready to plant, you can cut a hole through it and place the new plants into the opening. If you’re in a dry climate or your area is experiencing a drought, water the mulched area about once a week.

Laying Down Cardboard as a Weed Barrier

According to Modern Farmer, using cardboard as a weed barrier will benefit your garden in several ways. When combined with mulch, cardboard is exceptionally useful in keeping unwanted plants from growing or sprouting. Over time, the dead weeds and the cardboard biodegrade and feed the soil underneath with organic matter, boosting its nutrient content.

Cardboard and mulch trap moisture in the soil, further enriching it. Earthworms also love it – they thrive in its dark, moist habitat and add a layer of worm castings to the earth, which helps keep the area even more nutrient-rich. Using cardboard and mulch to kill weeds is inexpensive and easy to do. No tilling of the soil is required.

Cardboard and mulch are effective barriers in stopping the upward growth of unwanted weeds. Over time, cardboard and the dead weeds underneath it biodegrade and help create nutrient-rich soil.

Why Using Cardboard to Kill Weeds Is Effective

Cardboard that’s too compact can keep water and gases from nourishing soil microbes. If the cardboard sheet mulch dries out too much, it can repel rainfall and prevent moisture from seeping through. Cardboard sheet mulch can serve as an excellent alternative to herbicides in well-watered, well-maintained gardens. However, if yours is not consistently monitored, it can cause more problems with the plants you want to keep in your garden.