How to Solarize Garden Soil

If you live in a warm climate and have problems with nematodes or soil-borne pathogens, solarizing your soil might just solve your problems. With this simple method, you use sheets of clear plastic, which you place on top of the area you want to help, and the sun does the rest. Solarization can help to control tomato wilt fungus--both the fusarium and verticillium wilt. As a natural control, solarization can save gardeners and farmers many dollars that they might have spent on herbicides, fungicides and other pest control products. It replaces methyl bromide in its effectiveness. It’s ideal for many different kinds of crops, because it can control the pests that affect fruits, vegetables, nursery and orchard crops. Areas that have high summer temperatures experience the best success with solarization: daytime highs of 85 degrees Fahrenheit are ideal. The only drawback of solarizing your soil is that you need to leave the area you treat fallow for about six weeks in midsummer.

Difficulty: Moderately Easy

Instructions

Things You'll Need:

• Garden rake
• Water
• Clear plastic
• Rocks or soil to anchor plastic

1. In June, determine where you need to solarize and then purchase enough clear plastic to cover the area.

2. Disk, rototil or turn the soil by hand. Whichever method you use, be sure to break up clods and remove rocks, weeds and any other objects that might poke holes in the plastic.

3. Smooth the soil surface with a garden rake.

4. Thoroughly soak the area with water.

5. Lay the plastic over the area as soon as possible after watering it to prevent loss of moisture.

6. Anchor the edges of the plastic with soil or rocks to hold them securely in place.

7. Leave the plastic in place for about six weeks. Mid-June through mid-July is the best time, when daytime temperatures reach 85 degrees Fahrenheit or higher.

Tips & Warnings

• Attempt to place the plastic as close as possible to the smoothed surface of the soil in the area you want to treat.
• “Complete coverage” is a good way to solarize and involves covering an entire field, garden bed or any area. Or you can choose to use “strip coverage,” where you treat only selected portions of garden beds or fields. Complete coverage is best when you know that your soil is heavily infested with disease-bearing spores or pathogens, and is especially effective against nematodes. Strip coverage might not be the best method for controlling soil pathogens and nematodes because if you leave untreated areas in the rows between treated beds, the problem you are trying to get rid of can get into the treated areas in time.
• To create a larger plastic sheet, you can glue pieces together with ultraviolet resistant glue.
• To avoid water loss, be sure to apply the plastic as soon as possible after you irrigate the area you want to treat.