If you haven’t noticed, it’s hot outside – like really hot – but it’s amazing how the weeds still continue to grow! Soil solarization is sometimes considered the ‘holy grail’ of organic weed control since it does not require herbicides to work and because it is currently so hot outside, it’s the perfect time of year to talk about it! According to UC IPM – if done correctly, soil solarization will cause the top 6 inches of soil to heat to as high as 140°F – yep the magic composting number – the temperature required to cook many weed seeds – whoohoo!
Check out this fact sheet on soil solarization from UC IPM for more information on the many benefits of soil solarization and how to solarize effectively. Here are some recent photos of a local garden utilizing soil solarization among other organic weed control techniques.
Black plastic will exclude light to weed plants but black plastic will not heat up the soil temperature as well as clear plastic.
High weed pressure in a bed with exposed soil.
Clear plastic being used for soil solarization.
Beads of water under plastic from water vapor.
Evidence of impacted plants. Note, soil solarization is less effective for perennial weed control – like field bindweed pictured.