One of the most popular questions we get in our email inbox is on the topic of using cardboard as a mulch in the garden – or more to the point – can you safely use it in the garden to help keep moisture in the soil and stop weeds.
One thing is for sure, with the onslaught of online deliveries to the home, there is more cardboard available than ever before. But is it really safe to use as a mulch around vegetable plants whose produce we consume?
After all, doesn’t some cardboard contain glues, chemicals and dyes that can get into the soil, plants and yes, the vegetables and fruits we consume?
The short answer is that yes, there are some cardboard products you should avoid using near plants. But the good news is that the large majority of cardboard available today is not only safe to use – it can really help your garden in several ways!
Today’s article takes an in-depth look at which types of cardboard are safe to use – as well as how to use cardboard to help build better soil and stop weeds in their tracks.
How To Safely Use Cardboard In The Garden!
There really are a long list of benefits for using cardboard in the garden. For starters, with the ability to obtain it for free, it really is one of the most economical ways to stop weeds. See: How To Stop Garden Weeds With Mulch – For Good!
In addition, believe it or not, cardboard also can help improve the quality of soil. As it breaks down, cardboard helps to add valuable organic matter to the soil. Organic matter that not only increases nutrient levels, but also helps build better soil structure.
It also is incredible at helping to retain valuable moisture in the soil. And if that wasn’t enough, it also can increase earthworm activity in the soil below wherever it is used. But again, the secret to success is knowing which cardboard you can use – and which you can’t.
How To Know What Types Of Cardboard You Can Safely Use In A Garden
The good news is there are 100 percent compostable, dye-free cardboard products that are incredibly safe to use in your garden. And there are a few secrets to tell which cardboard boxes are safer than others.
For starters, look for boxes that have a dye-free and/or 100% recyclable stamp or label. Most cardboard boxes now have an organic stamp that identifies that it contains only safe and biodegradable material and glues. As an additional good “rule of thumb” use only boxes that are colorless and coating free.
There are cardboard products you will want to avoid entirely. Depending on how and where the cardboard is made, it can contain a long list of chemicals and glue compounds. Both of which can quite easily leach into the soil.
Add to that, many cardboard products also contain man-made ink compounds that can also soak into the soil as well. Some even contain small amounts of plastic that won’t decompose. Not only can these compounds and chemicals contaminate the soil, but they can also soak into the roots of your plants. That can be quite concerning, especially if you happen to be growing vegetables.
It’s also important to avoid cardboard with heavy wax coatings. Some cardboard boxes contain a thick waxy coating on the outside. The coating is put on the boxes to help waterproof them and their contents. A great example of this is a pizza box, which is often coated to keep heat in and moisture out.
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Unfortunately, when used in a garden setting, the waterproof coating can keep valuable moisture from getting to a plant’s roots below the soil surface. Even more, the coating also holds in moisture and gasses, trapping them under the soil. And that can increase the likelihood of a plant rotting out.
So now that you know which types of cardboard you can use and which you shouldn’t – let’s take a look at the best ways to use safe cardboard to stop weeds, hold in moisture – and build better soil!
The Best Places To Use Cardboard In The Garden – How To Safely Use Cardboard In The Garden
Cardboard is excellent for placing in the walking areas of your garden where plants are not growing. This keeps you from ever having to till or spend time taking care of these non-growing areas.
As for the look of the garden, many gardeners put down their layer of cardboard first. Then, they cover it up on top with straw, grass clippings or another organic mulch.
This provides even more protection from weeds and better insulation for the soil. But best of all, it also creates a far better look for the garden area too! Using cardboard like this also extends the life of your mulch on top as it can’t sink into the soil below.
You can also use cardboard around plants as long as you keep it away from the main stems 8 to 12 inches. It’s best not to place it too close because it can delay moisture and fertilizers from getting right to the roots. Instead, use natural mulches up close such as straw, shredded leaves or grass clippings.
Using Cardboard To Get Rid Of Stubborn Weeds – How To Safely Use Cardboard In The Garden
Cardboard can also be a great solution in flowerbeds for stubborn weeds. Thistle, quack grass and other tough to eliminate weeds can be hard to control with a mulch only approach. But by placing a few layers of cardboard underneath the mulch, you can finally snuff the weeds out for good!
In all of the situations above, remember it’s best to always use cardboard that is dye and coating free. Here is to using cardboard in your flowerbeds and garden safely – and to keeping those weeds down too! Happy Gardening – Jim & Mary.
Old World Garden Farms
Jim and Mary Competti have been writing gardening, DIY and recipe articles and books for over 15 years from their 46 acre Ohio farm. The two are frequent speakers on all things gardening and love to travel in their spare time.
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