Soil Solarization for Weed Control
You have a spot in the yard that you would like to develop into a flower garden or vegetable garden but it is over grown with grass and other types of weeds. You know if you just till it up that all those grass roots will regrow and the seeds present will germinate and grow. You don’t want to use a herbicide since. What can you do?
Soil solarization may be the key to getting the unwanted weeds under control. You still need to till the area and break up the sod. If you are going to apply manure or compost to the garden spot do it before you apply the plastic. The soil should be moist enough for seeds to germinate so the area should be watered before you apply the plastic.
The key to soil solarization is to use clear plastic to cover the desired area being sure that the edges are sealed so no heat will escape. The plastic should be thick enough not to tear when you are laying it down. The edges can be sealed with beach sand sold for children’s sand boxes. Rocks will help hold down the plastic so it doesn’t blow in the wind.
The plastic can’t have any rips or tears in it since these will vent the hot air and allow some perennial weeds to thrive like quack grass. If any tears develop use duck tape to seal the plastic and extend the solarization time.
The only time we can do this weed control technique effectively in Maine is during the hottest part of summer. The summer sun will heat the air under the plastic to well over 1400 F and kill weeds and seed in the top layer of the soil under the plastic. It may also provide some control of nematodes in the soil, too. The plastic should remain in place at least a month to be sure the heat has penetrated deep into the soil.
Once you remove the plastic the sand can be mixed into the soil. You can plant your vegetables or flowers. Think about using mulch to keep the weeds under control when your desirable plants are growing. Don’t add any fresh manure or use hay for mulch or you will undo all the work of the solarization.