Seeds disperse with agricultural and other human activities, water, soil movement, animals, and as crop seed and hay contaminants. Seeds are hard-coated and most float on water. Seed production and germination requirements are variable, depending on biotype and environmental conditions. Cool moist stratification enhances germination. Giant foxtail seed dormancy at maturity is variable, and seeds produced later in the season are often less dormant than those produced earlier.
Most seeds survive only a few years under typical field conditions.
Hand removal or cultivation as needed before seeds are produced can control infestations. Introduced from Europe. Knotroot foxtail is a native perennial with short , knotty rhizomes . It is widespread throughout much of the U.S, but relatively uncommon in California. Knotroot foxtail is usually not considered a weed in natural habitats.