Almost all vegetables are annuals. They complete their entire growth cycle in one growing season, produce seeds and then die. A few vegetables are biennials, but we grow them as annuals. If left in the ground to grow the following year, they produce flowers and set seed, ensuring the continuation of their species. Very few vegetables are perennials, growing back from their roots each spring.
Reliably emerging every year in early spring, asparagus is a true perennial vegetable. The spears are immature flower stalks, picked before the buds swell. Asparagus is only picked for 6 to 8 weeks each spring, as the plants need to flower and produce leaves to provide food for the roots to produce next year's crop of spears.
Primarily used as a fruit, rhubarb is in reality a vegetable. The stalks are the edible part; its leaves are poisonous. The stalks are cut up and made into jam, jelly, pie, crisps and quick bread. Rhubarb is one of the first crops to mature in spring. Its stalks are traditionally harvested until late June or early July. After that, it is left to grow and store food in its roots for next year's growth.
Jerusalem artichokes produce knobby, irregularly-shaped, starchy underground tubers. Its top growth is tall and its flowers resemble sunflowers, to which it is related. Harvest the tubers in late summer when the stalks begin to yellow and die back. Because you can never find and dig up all the tubers when harvesting, Jerusalem artichokes will regrow from the errant tubers, making it a perennial vegetable.
Chives and garlic chives, are popular herbs grown in home vegetable gardens. They are hardy to U.S. Department of Agriculture plant hardiness zone 3 and emerge from the ground in early spring. Other perennial herbs grown in the vegetable garden are oregano, thyme, sage and mint. These herbs are all relatively hardy, only requiring winter protection north of zone 5.