Celery can generally be harvested by the beginning of fall and if planted in blocks (not trench), it should all be lifted and stored before the first frost. It will stay fresh for several weeks in the refrigerator. Although it can be frozen, celery becomes mushy when thawed so is only used for flavoring in recipes.

Giant Prague Celeriac  (Apium graveolens var. rapaceum)
120 days — Pronounced "seh-LER-e-ak", and also referred to as rooted or German celery, this cousin to celery is not visually beautiful.  But inside its unsightly exterior lies an inner, wonderful beauty.  Often mistaken for the root of celery plants, it is usually overlooked in American grocery stores.  Shoppers from Northern Europe, however, will tell you that once the cream-white flesh is removed from its fibrous skin, it is crisp, smooth textured and mild.

It has a pleasant flavor of parsley and celery.  Commonly enjoyed as a first course at French bistros, it is served shredded and topped with a mustard / mayonnaise dressing.  It is also useful as a  flavoring in soups and purees.  Additionally, try them mixed with mashed potatoes, sliced thin and baked au gratin, or sautéed.  If your doctor allows, deep fried chips are a special treat.

Golden Self-Blanching Celery  (Apium graveolens)
90 days — A very old standard variety.  The plants are stocky, solid, thick, with the stalks blanching easily. It is vigorous growing with upright medium green foliage. The roots are round, smooth and have good inner quality with high yields.

Tall Utah 52-70  (Apium graveolens)
110 days — This variety produces eleven to twelve inch stalks on plants that reach about 30 inches in height and are a medium dark green, crisp, tender and tasty.  Released in 1953.

Cultivation:  Start transplants indoors from February into April.  Germination is affected by the interrelation of temperature and light.  The seed will germinate with soil temperatures below 50ºF if the temperature is held constant and the seeds are in the dark.  It will germinate at 70ºF if it in diffused light and germinate in temperatures up to 85ºF if there is a 10-degree difference between day and night temperatures.

Cover the seeds lightly with potting media, keep moist, but not wet.  Germination is very slow (sometimes up to 3 weeks) so be patient.

Set out plants when they are 3 to 5 inches tall in late spring after all danger of frost has passed.  Space them 12 inches apart in rows 12 inches apart.  Mulch to help maintain moisture.  They are heavy feeders and like rich, well-drained soil, loaded with organic matter.

As with many root vegetables, celeriac is at its peak in the fall.  Select roots that are somewhere about the size of a medium apple.  Too small and there will be little to eat once peeled.  Too large, and the flesh tends to be woody and dry.

In areas with mild climates, they should be allowed to remain in the garden and harvested as needed.  In areas of harsher freezing weather, they should be harvested in the fall and stored in slightly moistened sand or sawdust in the root cellar like you store carrots.  The roots will keep 3 to 4 months this way.  If you are raising them to save seed, they are biennials and therefore flower the second year.

Click here for an interesting treatise on raising celery published in 1898 by A. W. Livingston's & Sons.