Why You Should Put Cardboard in Your Raised Beds

It is a common problem to have a surplus of cardboard laying around and not knowing what to do with it. Instead of throwing it in the trash, an easy way to repurpose spare cardboard is to line them on the bottom of your raised garden beds. One frequently asked question is whether you can put cardboard in your raised beds. 

The answer is yes. You can line the bottom of your raised garden bed with cardboard and newspaper to block out weeds or act as a barrier against rhizomatous, weedy or invasive plants. While some may opt for landscape fabric, cardboard is a more cost-effective option. 

Frequently Asked Questions

What Kind of Cardboard Should You Use?

One concern gardeners have is the presence of chemicals and glue compounds in low-quality cardboard, which can leach into the soil. However, using dye-free or recyclable cardboard can assuage these fears – an organic stamp is a good indicator that it is safe for the garden. For best results, choose plain cardboard that has no tape and minimal markings in order to minimize the amount of chemical substances. Cardboard with a glossy coating or inks should be avoided. In most cases, cardboard typically found around the house is safe to use. 

         

Where Should You Put the Cardboard?

Other than putting it on the bottom of raised beds as lining, cardboard can be used to line walkways, flower beds, and other bothersome areas with thick grass or weeds. You can place soil or mulch on top of the cardboard without going through the trouble of tilling the dirt or getting rid of weeds. 

Where Can I Find Cardboard for Cheap? 

Cardboard is readily available for cheap at retailers like Walmart, or you can obtain them for free from friends, stores, or construction sites. You can also use grocery boxes or Amazon boxes from shipments. 

What Should I Put on the Bottom of my Raised Bed? 

You should put a layer of organic material at the bottom of your garden bed that will break down and enrich the soil. This can include compost, woody material such as logs, dry wood, branches, and leaves. Organic material is the best option, as it improves drainage as well as enriches the soil as it breaks down and does not need to be removed from your raised beds later. For a cost-effective way to save money, try the hugelkultur method, which incorporates the concept of layering organic waste to create a flourishing soil environment that mimics the natural landscape of a forest. 

          

Reasons Why You Should Put Cardboard Under Raised Garden Beds

For those that are budget conscious, cardboard is a salient way to suppress and kill weeds and grasses. However, if you are willing to spend more, landscape fabric and row covers are great alternatives in keeping pests and weeds from encroaching upon your garden. While the elevated height of raised garden beds should already deter the majority of weeds, some gardeners choose to add cardboard as a base layer for easy gardening. Just simply place the cardboard on your desired gardening location, install your raised garden bed over it, and fill it with soil. 

1. Easy Way to Prepare Your Garden Bed  

In the past, newspapers were commonly used as lining under garden beds – the advent of the Internet has since then rendered them obsolete. Cardboard is better than newspaper because it does not contain ink and is more durable. By layering flattened sheets of cardboard around your planting area, you can eliminate grasses and other surface vegetation on your turf by smothering them. 

To prepare your garden bed, line with cardboard, then dampen it thoroughly with a hose. Add around 6 inches of soil, compost, or mulch. After a couple of months, your garden bed should be ready for planting. This is recommended because it is less invasive and harmful than trying to dig it up or use chemical herbicides. You do not need to wait for it to decompose; the cardboard can also function as a barrier against weeds. 

          

2. Decomposes Quickly   

Cardboard is a relatively biodegradable material, taking 2 – 8 months to decompose, depending on the thickness, amount used, and environmental factors. Because of its ability to decompose quickly, you do not need to worry about removing it later. It will quickly degrade, adding organic matter to the soil and allowing nutrients to filter through. As it breaks down, the cellulose fibers in the cardboard get digested by microbes, which in turn enriches the soil. 

3. Prevents Weeds from Sprouting

One of the most important benefits of cardboard is its effective ability to suppress and kill weeds. It acts as a physical barrier to block out pernicious weeds. Usually, 2 – 3 layers of cardboard will suffice, though you may want layers in more weed-prone areas.

4. Creates a Conducive Environment to Earthworms 

The damp environment created by the cardboard is conducive to earthworms and other beneficial soil microorganisms. In addition to using cardboard in raised beds, you can also add it to vermicomposting bins, where it will serve as bedding and the occasional food source. For those looking for a low-maintenance vermicomposting bin, Vego Garden’s in-ground worm composter is an easy way to enrich your soil without the smell or hassle of traditional composting systems. 

5. Extra Protection Against Pests

If your plants have been plagued by burrowing pests such as gophers, voles, and moles, then cardboard can serve as added pest protection. Though not sufficient alone against those vermin, they can hinder it with the addition of a gopher net. While landscape fabrics are labeled as permeable, dirt and debris can accumulate over time, rendering it impermeable. With cardboard, you do not need to worry about this problem as it will quickly disintegrate, allowing nutrients and gases to seep through. It is recommended that you add in a layer of cardboard to your garden beds, then place netting above it to safeguard your plants.