Using Soil Solarization to Kill Weeds
If you have a problem with weeds in your garden or flower beds, but want to stay away from harsh chemicals, you should consider using soil solarization to rid the area of weeds. By using solarization, you heat the soil to levels that kill off weeds well below the surface, and keep them from reseeding themselves. The process is completed by covering the area in a thin layer of clear plastic. The plastic is sealed off so that no air can enter the soils surface. The plastic is left in place for a period of six weeks during the hottest part of the summer. This heats the ground to a temperature of up to 120 degrees.
If it is a garden you want to solarize, you may want to consider doing one half at a time, leaving the other half available for growing plants. After the six weeks and when the planted side has been harvested, you can alternate and solarize the other side.
Step 1 - Prepare the Soil
Pull any visible weeds from the soil before you begin. When the area is free of weeds, use a spade or tiller to work the soil to a depth of 8 inches. Be sure to pick out any more visible weeds as you work the ground. When the area is well tilled, rake the surface as smooth as you can get it. Water the area, enough to get it moist but not enough to saturate it.
Step 2 - Dig a Trench Around the Area to Be Solarized
The best way to make sure the plastic stays airtight over the soil is to bury the sides all the way around. Dig a trench that surrounds the area you will be covering. The trench should be 1 foot deep and 6 inches wide. If you use more than one sheet of plastic, use the heat resistant glue to attach the sheets securely so no air gets through.
Start at one corner of the area and begin to bury the plastic. You may want to go back and forth, from one side to the other to make sure you are able to keep the plastic tight all the way around. If any air pockets form, it is better to not have to dig up any of your already buried plastic. Pack the dirt around the plastic in tightly to make sure it stays in place. It will have to be able to endure storms and high winds.
Step 3 - Leave in Place for 2 Months
Leave the plastic over the area for 2 months. If the weather during this time is cool and the area has not received enough sun, you may need to leave it in place longer. When the time has passed, remove the plastic. You should be able to begin using it right away, and it will be weed free. If you are solarizing in sections, repeat the process on the next section.