Cardboard as Mulch: Simple, Smart, Sustainable

What Cracked Soil Taught Me About Mulching

We’re barely two weeks into the dry season, and the ground has already started to crack. I didn’t notice it at first—until the grass was cut and the soil was left exposed. That’s when the cracks appeared, running through the ground like tiny fault lines. What caught my attention even more was the contrast: in areas where I had laid flattened cardboard boxes months ago to control unruly grass, the soil beneath was still slightly moist, with far fewer cracks. That small, unintentional experiment reminded me of something we often overlook in our gardens—bare soil suffers, and mulching matters.

                                Bare soil cracks quickly once the dry season begins

A Dry Season Wake-Up Call

In the Caribbean, the transition into the dry season can be sudden and unforgiving. Once vegetation is removed, soil is left exposed to sun, wind, and rapid moisture loss. Cracked soil isn’t just unsightly—it’s a sign of stress, compaction, and declining soil health.

An Accidental Mulching Experiment

I originally laid cardboard on the ground simply to control grass that had grown out of hand during the rainy season. No grand plan. No soil science experiment. But when the dry weather arrived, the results were impossible to ignore. Under the cardboard, the soil remained darker, cooler, and noticeably more moist than the surrounding exposed ground.

                                    Under cardboard, the soil stays cooler and more alive

Why Bare Soil Is a Problem

Leaving soil uncovered allows moisture to evaporate quickly, soil temperatures to rise, and beneficial organisms to retreat deeper underground—or disappear altogether. Plants growing in these conditions experience more stress, require more frequent watering, and struggle to establish healthy root systems.

Cardboard as Mulch: Simple, Smart, Sustainable

Using cardboard as mulch checks a lot of boxes:

• It upcycles waste that would otherwise be discarded

• It suppresses weeds without chemical weedicides

• It breaks down naturally and adds carbon to the soil

• It encourages soil life as it decomposes

It’s not fancy, but it’s incredibly effective.

                Dead grass, millipedes and adding carbon to the soil as it decomposes-win,win,win!

Less Water, Fewer Weeds, Happier Plants

Mulching with cardboard reduces moisture loss, keeps soil temperatures more stable, and limits weed growth by blocking light. The result? Less watering, fewer weeds to battle, and plants that cope better with dry-season stress.

             The area under the cardboard is weed free. How's that for chemical free weed control?

What’s Happening Below the Surface

Lift the cardboard and you’ll often find signs of life—millipedes, insects, and rich, crumbly soil. These organisms play a vital role in breaking down organic matter, improving soil structure, and supporting plant health. Healthy soil isn’t silent; it’s busy.

                                                Millipedes at work — a sign of active, healthy soil

More Benefits Than You Might Expect

Mulch also reduces soil splash during watering or rainfall, lowering the risk of soil-borne diseases reaching plant leaves. It protects shallow roots from heat stress and helps plants lose less moisture through their leaves during extreme conditions.

Mulching Beyond Cardboard

While cardboard works beautifully, it’s not the only option. Leaves, grass clippings, coconut husk, and wood chips can all serve as mulch. The key is simple: keep the soil covered.

The Takeaway

Bare soil is vulnerable soil. Mulching doesn’t have to be complicated or expensive to be effective. Sometimes, the simplest solutions—like a flattened cardboard box—can make the biggest difference, especially during the dry season.

Has Cardboard worked as a mulch or any other visible benefit for you? Share in the comments. we'd love to hear from you. Who knows, you may just inspire another fellow gardener.

 Happy Gardening!

 The Grey -Haired Gardener