How many plants for average family:
3 or 4 per person

Type of plant:
annual

Best Varieties:
Tendercrisp
Giant Pascall
Celeriac is grown for tuber even though leaves are also edible.

Sowing:
Seed is slow germinating, so plants best purchased as seedlings. Plant out seedlings just at ground level making sure not too bury deeply.

Growing Habit:
Clumps spaced about 30cm apart.
Mature plant reaches over 50cm high.
Pick individual stalks as required or "blanch" to obtain pale, milder stalks and harvest whole bunch.
Blanching is done by wrapping plants in cardboard and tied with string to exclude light. Soil or mulch is hilled around plants to also give extra protection from light.

Growing Conditions:
Celery needs slightly acid soil with good drainage. Consistent water is required at final stage of growth to avoid black centres. Liquid feed fortnightly with nitrogenous fertiliser to keep stems from becoming tough and stringy.

Companions:
Beans, broccoli, cauliflower, cabbage, Brussels Sprouts, dill, lettuce, lovage, marjoram, peas, silverbeet, spinach.

Problems:
Poor drainage causes crown rot.
Black heart if water stressed.
Easily bolts to seed if not enough water or fertiliser.
Cracked stems are from boron deficiency.
Fungal problems if conditions too moist.

For more information:

Vegetable Gardening: How to Grow Celery
Information on how to grow Celery, one of the more difficult and demanding of vegetables to grow. Take up the challenge and grow Celery this season. ... How to Grow Celery. Celery is a vegetable that is popular with the health conscious ... Celery is not commonly found in the home garden, despite the fact that is is ...
http://www.gardenersnet.com/vegetable/celery.htm

FoodTale: CELERY
... "The thought of 2,000 people crunching celery at the same time horrified me" ... She leaned slightly toward him and looked modestly at the celery before her ...
http://www.soupsong.com/fcelery.html

The World's Healthiest Foods: Feeling Great
Non-profit foundation providing reliable, scientifically accurate, personalized information for convenient and enjoyable healthy eating. ... Celery. Celery has become a common household staple along with carrots, onions and potatoes ... enjoy the best taste and quality of celery during the summer months when it is in ...
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=14

Celery First Used as a Medicine
Celery First Used as a Medicine. Celery (Apium graveolens) is believed to be the same plant as selinon, mentioned in Homer's Odyssey about 850 B.C. Our word "celery" comes from the French celeri, which is derived from the ancient Greek word.
http://aggie-horticulture.tamu.edu/plantanswers/publications/vegetabletravelers/celery.html

Celery
... much a household staple as onions or potatoes, celery is valued for its crisp texture and distinctive flavor ... A bunch or head of celery is made up of individual stalks ...
http://www.wholehealthmd.com/refshelf/foods_view/1,1523,16,00.html