The Impact of Paper and Cardboard Ink on Your Garden Soil: Should You Worry?

What happens to the ink of papers or carboard boxes that you put down in your garden? Is this something we should be concerned about or is it negligible? This is what I think about on my drives into work :)!

When you spread paper or cardboard boxes in your garden, you might wonder what happens to the ink printed on them. Does it seep into the soil and harm your plants? Should you avoid using these materials in your garden altogether? This post explores what happens to the ink in paper and cardboard when placed outdoors, the potential risks involved, and practical advice for gardeners who want to use these materials safely.

What Happens to Ink on Paper and Cardboard in the Garden?

Paper and cardboard often contain printed ink, which can be made from a variety of substances. When these materials are placed in the garden, they begin to break down due to moisture, microbes, and exposure to the elements. During this decomposition, the ink can potentially leach into the soil.

Cardboard Box with Garlic Inside

The type of ink matters a lot:

• Soy-based inks: These are common in newspapers and many food packaging materials. They are made from natural oils and are generally considered safe for the environment. Soy inks break down more easily and have minimal impact on soil health.

• Petroleum-based inks: These inks contain chemicals derived from petroleum. They are more resistant to breaking down and may contain heavy metals or other toxic substances.

• UV-cured inks: Used in some high-quality prints, these inks harden under ultraviolet light and are less likely to leach but can persist in the environment longer.

  
  

Most cardboard boxes, especially those used for food or shipping, use soy-based or vegetable-based inks. However, some glossy or colored prints might use petroleum-based inks.

Are These Inks Harmful to Garden Soil?

The concern is whether ink chemicals can harm soil microbes, plants, or even enter the food chain through vegetables grown in the soil.

What Research Shows

• Studies on soy-based inks show they break down naturally without leaving harmful residues.

• Petroleum-based inks may contain heavy metals like lead, cadmium, or chromium, which can accumulate in soil and affect plant growth.

• The amount of ink on cardboard or paper is usually very small, so the risk of significant contamination is low if you use these materials in moderation.

  
  

Practical Risks

• If you use large amounts of glossy, colored, or heavily printed cardboard, there is a higher chance of introducing harmful substances.

• Using recycled cardboard or paper with unknown ink types increases uncertainty.

• Inks from newspapers printed with soy-based ink are generally safe and often recommended for garden use.

How to Use Paper and Cardboard Safely in Your Garden

Many gardeners use paper and cardboard as mulch, weed barriers, or compost material. Here are some tips to minimize any risks from ink:

• Choose plain or lightly printed cardboard: Avoid glossy or brightly colored boxes.

• Look for soy-based ink labels: Some packaging indicates the type of ink used.

• Remove tape, labels, and stickers: These often contain plastics or adhesives that do not break down well.

• Use paper and cardboard in moderation: A thin layer is enough to suppress weeds and retain moisture.

• Combine with compost: Mixing shredded cardboard with compost helps speed up decomposition and dilutes any ink residues.

• Avoid using printed paper with heavy ink coverage: Magazines, flyers, or glossy brochures may contain harmful inks.

  
  

Pigment or Dye Based in in Stamp Pads

Alternatives to Printed Paper and Cardboard in the Garden

If you want to avoid any risk, consider these options:

• Use plain brown cardboard without printing.

• Use newspaper sheets printed with soy-based ink.

• Use natural mulches like straw, leaves, or wood chips.

• Use composted paper products that have already broken down.

  
  

Final Thoughts on Ink in Garden Paper and Cardboard

The ink on paper and cardboard boxes can break down in your garden soil, and the risk it poses depends on the type of ink and the amount used. Most soy-based inks found in newspapers and many cardboard boxes are safe and degrade naturally. Petroleum-based inks and glossy prints carry a higher risk but usually only if used in large quantities.

For gardeners, the best approach is to use paper and cardboard thoughtfully:

• Prefer plain or soy-ink printed materials.

• Avoid glossy or heavily printed items.

• Use these materials as part of a balanced garden system with compost and natural mulches.

  
  

By following these guidelines, you can safely recycle paper and cardboard in your garden without worrying about harmful ink contamination. This practice supports sustainability and helps reduce waste while benefiting your soil and plants.

Keep an eye out for petroleum-based inks! Those you do not want in your garden.

~DIY With Chelsea