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Dallas Morning News - May 1, 2019

Plastic Out — Save Money

I have a tip that will save money on your next landscape project. It will also save time and management costs. Use no plastic. That includes solid plastic sheets and the so-called weed-blocking “fabrics”. These things are promoted to help prevent weeds. Problem is – they don’t work very well, waste money 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 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 fabrics were used at the time of planting 
Negatives are several. 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 breathability and plant roots suffer from lack of air and some cases water.  

Plastic sheeting increases soil temperature and blocks the proper exchange of oxygen and carbon dioxide
 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 should be the place where the most important things are happening. The surface of the soil, just under the natural mulch, is where the ideal temperature, the ideal moisture level, the ideal fertility and an ideal 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. 

What to do instead? Mulch!

  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? 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 used after new beds are prepared greatly helps 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.  


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