Soil Solarization: Why Clear Plastic Works and Black Doesn't

The Physics

• Clear plastic: Transmits sunlight; heat builds up underneath, killing weeds, seeds, pathogens.
• Black plastic: Blocks light; only kills annual weeds by shading. Reflects heat, so soil doesn't get hot enough.

Timing Is Critical

Solarization only works in summer heat. Winter covering provides minimal benefit regardless of plastic color.

Practical Compromise

Black plastic now will suppress some weeds, but true solarization requires clear plastic in June–August.