Onions, Shallots, Leeks, and Scallions

This genus includes a variety of edible crops such as onions, shallots, leeks, and scallions (a.k.a. green or spring onions). While onions and shallots are cultivated for their bulb, leeks are cultivated for their stalk. Spring onions are typically immature onions harvested before bulbing occurs. There are other scallion varietals like Chinese scallion and Welsh onion. Chives are also part of this genus but are typically treated as a perennial herb.

Although temperature, soil health, pest pressure, and watering also influence onion growth, the number of hours of daylight determines when onion plants begin to bulb. When the required number of hours is reached, onions switch focus from leaf growth to bulb formation. Onions are classified into three categories, depending on where you live.