Tackle Weeds the Natural Way
Solarization is especially effective for controlling annual weeds and pests in gardens with plenty of sun and available moisture. It can be used in raised gardens as well as areas slated for new lawns. More detailed research information and technical data on solarization can be found here and here. More: 5 Ways to Naturally Win the Weed War5 Weed-Smothering Ground Covers
Cover the soil surface with clear (preferably UV-stabilized) plastic, 1.5 to 3 millimeters thick. The plastic must be held tightly against the soil surface; secure the edges by burying them 5 to 6 inches into the soil.Note: Thinner plastic is less expensive and may be used in a double layer, but is more prone to wind or animal damage. In cooler climates, using black plastic for a longer period of time may be as effective as clear plastic.Four to six weeks of solarization during the long, hot days of summer are enough to kill most weed seeds and soil pests. In the cooler days of fall and spring, six to eight weeks may be necessary.
Solarization uses radiation from the sun plus moisture to heat soil to 99 to 125 degrees Fahrenheit. This treatment not only kills weeds and weed seeds, but also soilborne pathogens such as fungi, parasitic nematodes, insects and some bacteria. Soil solarization also speeds up the breakdown of organic matter in the soil, resulting in more available nitrogen, calcium, magnesium and potassium. It’s a simple, chemical-free way to revitalize an old planting bed or prepare a new one. How to solarize weeds:Rototill or spade existing plant material and additional organic matter (chicken manure, grass clippings, etc.) into the soil. Decomposing organic matter contributes additional heat to the process and can also protect soil microbes. Rake the soil smooth and lump free — the goal is a clean, flat surface.Wet the soil to a depth of 12 inches (the moisture is critical to conduct heat through the soil). Keep the soil moist throughout the solarization period.
Smothering is simply an exaggerated form of mulching. A thick layer of paper or cardboard, topped by several inches of organic matter, deprives existing weedy plants of light, thus inhibiting their growth. By using organic materials that decompose quickly, you also get the benefit of composting. Plant directly into the smothered area once the existing weeds are conquered. How to smother weeds:Mow or chop the existing vegetation in the area selected for future planting.Spread a layer of newspaper (exclude colored pages), newsprint or brown kraft paper (eight to 12 sheets thick), or three to four layers of cardboard. Be sure to overlap paper edges so there are no gaps.Saturate with water.Cover the entire paper area with a 4-inch-layer of organic material — shredded wood fiber, wood chips, pine needles, cocoa hulls, etc. Alternatively, an 8-inch-layer of lighter materials, such as dried leaves, grass clippings, or weed-free straw, may be used.Let the area rest through the fall and winter.This technique works for areas both large and small, in the sun or in the shade. It’s not a cure for noxious, perennial weeds that have aggressive root systems, but it’s fairly successful way ...