Cardboard boxes are readily obtained for free from grocery and other stores. Cardboard is the best material to use for weed control in large areas, and you don't have to remove the grass first, as the cardboard is heavy and thick enough to kill it. Cardboard is wonderful for use when laying out a large bed or as a base for a lasagna garden or raised vegetable bed.
For best results, you should use two layers of cardboard. Lay the first layer, slightly overlapping the pieces, then lay the second layer, staggering them to cover the overlapped edges, much as you would lay bricks. If you will be planting in the ground underneath the cardboard, cut your holes now. If not, start piling on your mulch, soil, or organic matter. The cardboard will last long enough to kill anything underneath it and will eventually decompose and become part of the soil.
By recycling these biodegradable materials in your garden, you will not only control weeds, but you will enrich your soil and reduce waste. If you don't reuse your paper and cardboard, rememer to put it in the recycling bin. It's a proven fact that paper products buried under tons of garbage do not break down, as they are broken down by aerobic bacteria, which can't survive in landfills. It's a win/win situation for everyone when you recycle biodegradable materials into your garden.
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All information and instructions contained herein are from the author's own knowledge and experience.