Solarization is the process of using plastic to heat up the garden soil over a period of weeks or months. This technique is used to kill off all pests and diseases that overwinter in the soil, including fungus, bacteria and harmful nematodes.
The solarization process works best when all soil is an equal distance from the plastic. This provides uniform heating. Remove all plants, sticks, and other yard waste. Use a hoe and a rake to break up the soil and smooth it out as level as possible.
Use a garden hose to moisten the soil to a depth of 12".
For raised beds where the plastic will not rest directly on the soil, use clear plastic. The space between the plastic and soil creates a warming greenhouse effect. In situations where the plastic will rest directly on the soil, use black plastic. The black color absorbs more heat and transfers it directly to the soil.
Pull the plastic as tight as possible across the surface of the raised bed or soil. Use landscape staples or other fasteners to keep the plastic firmly in place. The object is to keep the wind, rain and weed seeds out of the bed. Keep the plastic in place until it is time to plant in spring.
The best time to start the solarization process is during hot weather. For the best results, begin in July or August.