Old flower spikes may persist into winter and consist of bristles and spikelet stalks with cup-shaped tips after spikelets have fallen. Yellow foxtail spikes are typically yellowish, while those other foxtails become brown. Disturbed sites, roadsides, ditch banks, fields, pastures, cropland, orchards, vineyards, gardens. All tolerate a broad range of environmental conditions and grow in moist or dry soils. Yellow foxtail also grows in turf and is most frequent on moist soils.
Giant foxtail grows best on fertile sandy soils.
Reproduce by seed . 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.