In the past, Celery was only grown as a vegetable for winter and early spring, but now it is available for most of the year. It is used around the world as a vegetable for the crisp leaf stalk and is most commonly used in salads, but it is also a staple ingredient in many soups, such as chicken noodle soup. The leaves are strongly flavoured and are used less often, in soups and stews or as a dried herb. Harvesting occurs when the average size of Celery in a field is marketable and the fields are harvested only once.
In Europe the dominant variety of Celery most commonly available in trade is Celeriac. The wild form of Celery, known as “smallage”, has a furrowed stalk with wedge-shaped leaves. The whole plant has a coarse, earthy taste and a distinctive smell. The stalks are not usually eaten, but the leaves may be used in salads and the seeds are those sold as a spice.
In temperate countries, Celery is also grown for its seeds which yield a valuable volatile oil used in the perfume and pharmaceutical industries. They also contain an organic compound called apiol. Celery seeds can be used as flavouring or spice, either as whole seeds or ground and mixed with salt, as celery salt. Celery salt can also be made from an extract of the roots, or using dried leaves. Celery salt is used as a seasoning, in cocktails, most notably to enhance the flavour of Bloody Mary cocktails.
Choose Celery that looks crisp and snaps easily when pulled apart. It should be relatively tight and compact and not have stalks that splay out. The leaves should be pale to bright green in colour and free from yellow or brown patches. Sometimes Celery can have a condition called “blackheart” that is caused by insects. To check for damage, separate the stalks and look for brown or black discoloration. The Celery should not have a seed stem as these are often more bitter in flavour. You can leave your Celery in a plastic bag, squeeze out any extra air and close the bag securely for storage in your refrigerator. While food storage in plastic bags can create health risks under certain circumstances, 5-7 days of refrigerator storage for an uncut head of Celery is fine. You should wait to chop up your Celery just before you are adding it to a salad or cooked dish. Freezing will make Celery wilt and should be avoided unless you will be using it in a future cooked recipe.
The use of Celery seed in pills for relieving pain was described by Aulus Cornelius Celsus around AD 30. They contain a compound known as 3-n-butylphthalide that has been demonstrated to lower blood pressure. Celery can also be used in weight-loss diets, where it provides low-calorie dietary fibre bulk.
Celery is among a small group of foods headed by peanuts that appear to provoke the most severe allergic reactions, causing potentially fatal anaphylactic shock.