Winter Queen is another popular, largely grown late variety. It doe's not attain as great a height as Giant Pascal, and is more convenient to store.

French Success is a stocky, compact winter variety of excellent keeping qualities.

Boston Market, a low, dwarf-growing variety, is especially popular in Boston. When thoroughly blanched with soil the stalks are extremely tender and delicious in flavor. No variety excels it in quality.

Many other varieties are described in the seed catalogs and some of them are excellent.

400. Climatic Requirements

Celery is grown successfully in all parts of the United States. Certain climatic conditions, however, are known to be especially favorable for its most successful culture. Low humidity, plenty of sunshine, considerable warmth during the day and cool nights provide ideal conditions. Diseases are less troublesome when the air is dry, and a rapid but strong, healthy growth is encouraged by sunshine and relatively high, dry temperatures. Cool nights make the stems firm and crisp. Most northern sections provide excellent conditions during summer and fall, while some parts of the South, especially Florida, possess the proper climatic conditions for winter culture.

Although celery is one of our hardy vegetables, it will not stand severe freezing without sustaining injuries. The young plants are likely to be checked in growth by hard spring frosts which probably cause them to produce seed stalks. The matured plants are often damaged or killed by severe freezing. Vigorous plants will generally stand a drop of seven degrees below freezing, although this will impair the keeping quality. A liberal rainfall, well distributed during the growing season is necessary unless irrigation is possible.

401. Soils

The great commercial plantations of celery in the states bordering on the Great Lakes, in California and in Florida are upon muck soils. In Florida these areas are known as "hammock soils" and "saw-grass marshes." They vary from I to 10 feet or more in depth and are formed of decayed vegetable matter. There should be a depth of not less than 18 inches of muck to secure the most satisfactory results. In the best celery mucks the water table is about 3 feet below the surface. In such soil the crop will not suffer seriously during drouth. When the water table is near the surface the soil is soft and difficult to work with horses and there is also danger of an excessive amount of water in wet seasons.

The following is an analysis of a Kalamazoo muck soil (Mich. Sta. Bul. 99, p. 12) used for celery:

Percent

Sand and Sillicates ..............

19.16

Alumina ................

1.40

Oxide of iron ..............

3.94

Lime ...................

6.09

Magnesia ...................

0.81

Potash .....................

0.34

Soda .....................

0.38

Sulphuric acid ..................

1.31

Phosphoric acid ...................

0.88

Carbonic acid ...................

1.95

Organic matter (containing 2.53 of nitrogen)___

63.76

Water ......................

6.51

Other analyses published in the bulletin referred to indicate that there is very little variation in the composition of Michigan mucks.

When cleared muck soils are often very acid and require large applications of lime before they will produce the best crops of celery. The accumulation of alkalies in irrigated lands of the West is not apparently injurious to the growth of celery. A first-class muck is brown-black in color, friable, free from coarse, fibrous material and will produce no change on blue litmus paper. Sour mucks are unfit for cultivation until, in addition to liming, they are weathered by being exposed to the action of frost during the winter.

Muck soils are especially adapted to celery because they are moist, fertile, loose and friable; they are also easily worked, so that it costs less to grow a crop in such lands than in other soils. It is very generally admitted, however, that the characteristic flavor is somewhat lacking when celery is grown on muck soils.

While muck soils possess marked advantages for very extensive cultivation of the crop, splendid returns may be obtained on any soil that is deep, moist, fertile and well drained, sandy loams being preferred. Many clay and silt soils produce excellent crops, especially when well manured and irrigated. The introduction of modern methods of garden irrigation has made it possible to grow this crop at a profit wherever favorable market conditions can be found.

402. Sources Of Seed

The planting of high-grade seed is of prime importance, for poor seed may cause pithy or hollow stalks, a running to seed the first year, a failure to get a good stand of plants, and a lack of vigor and uniformity. Practically all of the seeds of the self-blanching varieties are grown in France. Excellent seeds of the green sorts are produced in California. Growers of the Boston Market use seeds produced near Boston. Since great skill and care are required in the growing of celery seed, gardeners should purchase their supplies from the most reliable dealers. Some commercial growers import from specialists in order to be absolutely certain of getting good seed. This is unnecessary, however, if the most reliable dealers in this country are patronized.

Fresh seed is advocated by most growers, although a few careful gardeners prefer to buy large quantities from various sources, and then use the best from year to year until the supply is exhausted. If kept in sealed glass jars where the temperature does not vary greatly, the germinating power of the seeds will be retained from six to eight years. The plants from very old seeds lack vigor and are probably more susceptible to disease than those from fresh seed.

403. Propagation

It is seldom best to sow for the early crop before March 1 in most northern sections., If sown earlier, special care must be exercised to avoid checking the growth before the plants are set in the field, for the fact seems to be well established that any hindrance of growth in seed bed, cold frame or field will be likely to cause seed production the first year. As the plants cannot be set in the open with safety until after May 1, it is difficult to maintain an unchecked growth when the seed has been sown very much before March 1.