No Plastic – Organic Answers Column – July 10, 2024
Plastic Garden Fabric — Don’t Use It
Planning another landscape project? I have a tip that will save you save time and management costs now and grief in the long run. Use no plastic. That includes solid plastic sheets and the so-called weed-blocking “fabrics.” These products are promoted to help prevent weeds but they don’t work very well and actually create some unnecessary problems.
The proponents for using plastic sheets under mulch mention benefits such as discouraging weed seed germination by stopping sunlight from reaching weed seeds. Of course, proper use of natural mulches, or timely application of corn gluten meal, does the same thing. They also talk about the plastic reducing the need for harsh weed control chemicals. Of course, we don’t recommend those toxic products at all. Conserving soil moisture is also mentioned. Once again, proper installation and maintenance of natural mulches does the same thing with lower cost.
Plastic sheeting increases soil temperature and blocks the proper exchange of oxygen and carbon dioxide. And looks bad!
There are many negatives. Besides increasing soil temperature and blocking the proper exchange of oxygen and carbon dioxide, the plastic fabrics are in the way every time a new plant is added, plus the fabric becomes more useless because of the holes. The natural organic fertilizers, amendments, and mulches can’t reach the ground to feed the soil and work their magic. Plastic restricts movement of soil-mixing organisms such as earthworms, insects, beneficial bacteria and fungi through the different layers of the soil. Over time, soil underneath the plastic loses breatheability and plant roots suffer from lack of air and some cases water. Stinky anaerobic zones can result.
These trees suffer as plastic inhibits good soil health
Plastic sheets are a total waste of money but the strongest negative is that plastic sheets or fabrics hurt the most important part of the soil – the surface. The surface of the soil is the place where the most important things should be happening. The surface of the soil, just under the natural mulch, is where the ideal temperature, moisture level, fertility and balance of beneficial biological activity is – or should be. If a piece of plastic is in that space, all these balanced ideal conditions are undermined or damaged.
Are there good uses for plastic landscape fabric? Yes, it’s an effective tool to use under gravel in utility areas where there are no plants, including nearby trees.
What to do instead? Use Mulch! Natural mulch will block sunlight needed for weeds to germinate and grow. Just don’t pile it up on the stems of plants. The natural pre-emergent herbicide, corn gluten meal can be used after new beds are prepared to prevent weed seeds from germinating. If you are determined to use some “blocking material” under the mulch, try paper or cardboard. You won’t have to worry about clean up since paper safely dissolves into the soil.
