I love celery. In my house no meal is complete without it. My wife will not make a soup without stealing the outer stalks from the celery that grows near the kitchen. Chicken stuffing is not complete without small, succulent pieces of celeriac, and I'm not even talking salads yet. I've been lucky enough to travel and learn how Europeans use celery, and as a seedsman and part-time breeder, I've grown celery -- lots of it.
Sowing and Harvest Timeline
Celery needs approximately three months as a seedling and three months in the garden. Gardeners living in USDA Hardiness Zones 8 to 10 can direct-sow seeds in November or December for a May or June harvest. If you live farther north or inland, plan to sow seeds indoors 10 to 12 weeks before the average date of the last frost for your area.
The standard American market celery is a Pascal type. These are listed in seed catalogs as 'Tall Utah' or 'Florida' strains, or simply as Pascal types. They were developed in response to the need for a celery resistant to heart-rot disease.
More recently, celery breeding has been directed toward tolerance to a new strain of the same disease, and most of these varieties are crosses with celeriac. These newest celeries, such as 'Peto 285', are even more disease tolerant, but their texture is tougher and the flavor is stronger so they aren't necessarily the best choice for the home gardener.
'Ventura' is a tall, upright grower with an attractive heart and is widely adapted. 'Utah 5270 R' (compact, thick stalks) and 'Utah 5270 HK' (uniform dark green) are both reselections of much older strains and have been available for at least two decades.
The second kind of celery is called "self blanching." These have slightly broader, more tender stalks and a natural pale yellow color. Varieties in this category are 'Golden Self-Blanching' (noted for earliness) and my favorite, 'Stokes Golden Plume' (early, with an attractive heart, blanches easily), which I believe is the best celery for home gardeners.
Celery is a cool-weather crop, preferring temperatures between 58° F and 80° F to do best. It needs rich, well-drained soil with a pH between 5.8 and 6.7. Most important, celery must have uniform moisture. Be prepared to use a good mulch on your crop.
Celery seed improves with age. In fact, you shouldn't plant seed that is less than three years old. There are two benefits to the older seed: Seed-borne leaf-blight diseases cannot survive that long, and with aging, the natural germination inhibitor in celery seed is overcome.
Use a good seed-germination soil mix . I prefer plug trays, but any kind of container in which seedlings remain individual works well. Germination occurs best when temperatures alternate between 60° F at night and 72° F during the day. Keep soil moist, and you'll see seedlings within three weeks. Thin to one plant per cell or container.
The emerging plants are delicate, so continuous moisture is essential. Once plants are three to four inches tall, the roots fill the plug and the plants are ready for the garden. Do not harden off celery by reducing temperatures, however. Rather than toughen plants, this can induce seed-stalk development. Transplant into the garden one week prior to the average last frost date.
Incorporate 6 to 10 cubic feet of compost into the top six inches of a 100-square-foot bed prior to planting. Set seedlings 8 to 10 inches apart, and mulch with any material that will not interfere with drainage (I prefer straw). Keep seedlings moist, and feed with a liquid fertilizer, such as a 20-30-20, every 10 days.
If you live in a mild-winter area, you can sow celery seed directly into the garden. Sow the seed thinly and cover with 1/8 inch of soil. After germination, thin seedlings until you have 8 to 10 inches between plants. Remember to mulch as soon as the plants are tall enough not be damaged.
Blanch stalks of either Pascal- or self-blanching-type celeries by wrapping the stalks in a brown paper bag once they reach 18 inches. Tie off the bag with string or a rubber band, leaving the top six inches of leaf exposed. In 12 to 14 days your blanched celery will be tender and sweet.
Problems and Pests
Black heart, the main cause of celery demise, is caused by uneven soil moisture. The first symptom is browning of leaf tips, but the disease soon spreads to the heart tissue. Avoid leaf blights by sowing seeds that are three years or more old. For the occasional aphid I use rotenone; for cabbage loopers Bt (Bacillus thuringiensis).
Cutting celery looks like flat-leafed parsley, but is loaded with celery flavor. In Holland it is used to flavor soups and stews. Harvest cutting celery when it is 15 inches high. Dry by hanging the stems and leaves upside down in a well-ventilated location. Grow cutting celery just like common celery but with one exception: Don't thin seedlings in your plug or pot. Simply transplant clumps to the garden, spacing them about six inches apart.
Celeriac is the cooking celery of northern Europe. It looks like our common celery, but stalks are thinner and much tougher and are generally considered inedible. It's the knoblike root that's the prize. Peeled and diced, it can be used anywhere you would celery. Or peel and julienne it, then steam and serve it as a cooked vegetable, perhaps with a few slices of carrot added in for color. Celeriac varieties include 'Brilliant' (smooth, medium size, resistant to hollow heart), 'Giant Prague' (vigorous, old-fashioned, open-pollinated) and 'Monarch' (large roots with firm, white flesh).
Peter Kopcinski is a seedsman based in New Jersey.