Using Cover Crops to Suppress Garden Weeds Frequent weeding during summer heat is labor-intensive. An alternative to manual removal or chemical herbicides is the use of cover crops (siderates) to preemptively block weed growth through biological competition. Cover crops function by competing with weeds for sunlight, water, and space. Many species also employ allelopathy—the release of specific chemical compounds that inhibit the germination of weed seeds. To prevent aggressive weeds from colonizing empty spaces, gardeners can implement soil rehabilitation after the harvest. Crop Primary Advantage Mustard Rapid growth and creation of dense above-ground biomass Phacelia Weed suppression and pollinator attraction Research indicates that mustard and phacelia can provide up to 90% soil coverage within eight weeks. This dense canopy deprives weed grasses of light, causing them to perish. For this method to work, every available patch of earth must be sown without leaving gaps. Sowing typically occurs in August or September immediately after a plot is cleared.

University of Wisconsin research is evaluating how the chemical makeup of cereal rye can impact crop development when used as a cover in rotations. Forage specialist Marta Kohmann tells Brownfield allelopathy levels in cereal rye, or natural compounds that reduce emergence and growth in other plants, can be problematic. “So far, our preliminary results show […]

University of Wisconsin research is evaluating how the chemical makeup of cereal rye can impact crop development when used as a cover in rotations. Forage specialist Marta Kohmann tells Brownfield allelopathy...

Allelopathy is how plants chemically help or harm each other. See the garden plants to pair, the ones to keep apart, and why fennel ruins carrots.

Allelopathic plants like black walnuts release natural chemicals that can inhibit vegetable growth and disrupt garden productivity. This guide explains how allelopathy works, which plants are affected...