An integrated weed management program is essential for onion and garlic production because of the unique challenges posed by their planting densities and susceptibility to weed competition. These crops are slow-growing and shallow-rooted, planted at high densities, and susceptible to severe yield loss from weed competition. Their narrow, upright leaves do not compete well with weeds, and their long growing season allows for successive flushes of weeds. Weed control is often challenging in these crops because few herbicides are registered, mechanical cultivation is often limited in high-density plantings, and hand-weeding can be costly. A good integrated weed management plan can increase the ease and effectiveness of these management tactics. Planting densities for onion and garlic pose unique challenges to weed management. These crops are sown at high plant densities and are not thinned to produce the greatest possible yield per acre. Onions are planted with 4 to 10 seed lines on beds that are 40 to 80 inches wide (furrow to furrow), or 36 inches wide in the intermountain area. Garlic is typically planted with 2 to 4 seed lines on 40-inch beds. These planting configurations limit cultivation to the furrow and narrow row middles on the bed top. Emphasis must be placed on techniques that reduce weed pressure before planting, such as the use of the stale seedbed method, weed-free seed, or soil solarization. Any method that reduces the amount of weed seed in the soil will reduce weeding costs during crop production. Another good way to prevent weed problems is to control existing weeds before they go to seed.