Oats

Sowing: Oats are direct-sown, with seed placed 1 to 2 inches deep in drills into moderately fertile, well-drained soil in full sun. They tolerate wetter soils than most other grains, though results are best where the ground is not subject to flooding, and they can also handle low-nutrient, acid soils. Because oats need less summer heat and more moisture than wheat, barley, or rye, they should be allowed at least ten weeks of cool-season growth.

Weed suppression: Oats grow thickly and vigorously, smothering and outcompeting weeds, and release chemicals into the soil that inhibit the germination of other plants. Where oats have been grown as a cover crop, gardeners should wait at least three weeks after the stand dies down before sowing vegetable or ornamental seed, giving these inhibitory chemicals time to degrade.

Grown as a cover crop, oats have few pest or disease problems and are relatively free of disease compared with other cereal grains. They are not a host for certain nematodes, which makes them a useful crop in rotations where those pests are a concern.

The oat grain matures and is harvested in spring.

Culinary: Oats are grown as an edible cereal grain, harvested and then processed into oat groats, steel-cut (Irish) oats, stone-ground Scottish oats, rolled or old-fashioned oats, or quick and instant oats depending on how the kernel is cut, steamed, or flattened; the grain must be cooked before it is eaten.

Forage and cover crop: Oats are also grown as livestock forage and, in home gardens, are most often sown in autumn as a winter cover crop or green manure that is later turned into the soil.

Oats were domesticated in the region of present-day Iran and Iraq, and the species name sativa is Latin for 'cultivated.' They appear to have entered cultivation as a secondary crop, their seeds resembling those of other cereals closely enough to be gathered alongside them by early farmers rather than being sought out deliberately.

Genetic evidence traces cultivated oats to the wild species Avena sterilis, with domestication occurring independently in the Fertile Crescent and along the North African and Iberian coasts, giving rise to what became known respectively as common oats and byzantina oats. Oats reached Europe later than wheat and barley, apparently spreading as a contaminant of traded seed grain and initially regarded as a weed before becoming an established crop by the 1st century; Romans introduced the crop to the British Isles, where it flourished, particularly in Scotland. Oats were carried to the Americas in the early 17th century by Spanish colonists in the south and by German and English settlers in the north, where they were long grown chiefly as feed for horses and livestock.