Mulches contribute to weed management in organic crops by reducing weed seed germination, blocking weed
growth, and favoring the crop by conserving soil moisture and sometimes by moderating soil temperature. Opaque
synthetic mulches like black plastic provide an effective barrier to most weeds and are amenable to mechanized
application, but they must be removed at the end of the season. Organic mulches like straw suppress annual weed
seedlings, conserve moisture, and add organic matter as they break down, but they are more labor-intensive to
apply. This article examines uses, advantages, and limitations of different mulching systems for weed control in
organic vegetable production. Two companion articles provide additional information on organic mulches and
synthetic mulches.