Don’t Toss Old Cardboard! 5 Ways to Reuse It in Your Garden for Better Soil and Fewer Pests

Growing your own vegetables and flowers is both eco-friendly and budget-friendly, but purchasing new and one-use garden products isn’t. That’s why giving materials you already have on hand a new life in your garden is a win-win for you and the environment.

There’s one material that you probably already have in abundance that has multiple gardening uses, and that’s cardboard. Professional gardeners have been using cardboard as a gardening tool for decades. Regardless of how you use it, it will always have the added benefit of improving soil health.

“Unlike plastic, cardboard naturally breaks down over time,” says gardener Linda Vater. “It contributes to healthy soil structure by enriching soil with organic matter as it decomposes, rather than introducing non-biodegradable waste or microplastics into the environment.”

We asked Vater to share some of her favorite ways to use cardboard in the garden, and she delivered.

Use Cardboard as a Weed Barrier

Skip the plastic weed barrier and chemical sprays, because cardboard can do the job of both. One of the most popular ways to reuse cardboard in the garden is as a weed barrier for your garden beds.

“Cardboard effectively blocks sunlight, hindering weed growth and suffocating them without the need for harmful herbicides,” Vater says.

Here’s how Vater uses cardboard as a weed barrier:

1. Lay down cardboard in sheets, overlapping the edges by six inches to prevent weeds from growing through the gaps. 
2. Wet the cardboard to keep it in place and initiate the decomposition process.
3. Top it with a 3- to 6-inch layer of organic mulch like wood chips, straw, leaves, or compost. This will hold the cardboard in place and further suppress weeds.

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Use Toilet Paper Tubes as Seed Starting Pots

Instead of tossing the cardboard tubes at the center of your toilet and paper towel rolls, use them as seed starting pots. Cut paper towel roll tubes into fourths and toilet paper roll tubes in half, and they’ll be the perfect size.

According to Vater, these make the perfect seed starting pots for multiple reasons. Cardboard naturally retains moisture, so your seedlings will be less likely to dry out if you forget a watering session.

Additionally, you can plant them into the ground, cardboard and all, since it will biodegrade. This will minimize root disturbance for delicate sprouts.

Add Shredded Cardboard to Your Compost

In terms of compost vocabulary, there are green materials and brown materials. Green materials are rich in nitrogen or protein, while brown materials are carbon or carbohydrate-rich. A ratio of three to four parts brown material to one part green material is ideal.

“Shredded cardboard, including toilet paper roll [tubes], makes an excellent brown ingredient for your compost pile, helping to balance the green material,” Vater says.

In addition to cardboard toilet paper rolls, cardboard egg cartons are also great for this use.

Use Cardboard as Vine Protectors

Young plants can often use some extra protection from frost, heat, and wildlife until they become more established. While you can purchase vine protectors new, they are actually made pretty similarly to toilet paper roll tubes.

Vater often uses cardboard tubes as vine protectors by cutting them lengthwise and fitting them around the base of the plant. Then, push it slightly into the soil to provide temporary, biodegradable protection.

Attract Worms, Snails, and Slugs With Cardboard

Slimy insects do wonders for improving soil health. Worms, snails, and slugs help organic matter decompose in soil faster. They also help with soil aeration since they create small channels in the soil as they burrow.

You can attract these insects to your garden by using damp cardboard.

“Lay damp pieces of cardboard on the soil overnight,” Vater says. “In the morning, lift the cardboard and relocate it to another area of the landscape.”

Vater also recommends adding shredded pieces of cardboard to a worm composter to encourage earthworm activity.