It should be stretched tight and in direct contact with the soil surface. Care must be taken to bury the edges of the tarp in the soil to a depth of at least six inches so as not to allow the wind to lift the tarp during the solarization period. Remember, the tarp has to remain in-place for a four to six week period. When removing the tarp, avoid contamination of the treated area with untreated soil. This is also true at planting and best results are obtained when beds are prepared for planting before solarization and immediately planted after removing the tarp.
Solarization also controls other soilborne organisms such as fungi, insects, and certain weeds.
However, the technique is probably most effective for reducing nematode populations in the top eight to ten inches of soil. For additional information on soil solarization, or control advice on other garden pests, check with us at the County Extension Office. Recommendations on this web site do not endorse any commercial products or trade names.