The eggplant is thought to have been originated in the East Indies, although there is no definite information concerning its early history. It is generally grown in tropical countries, and is an important vegetable in the United States. The southern and south Atlantic states, New Jersey and California, grow large quantities for commercial purposes. In the cooler regions of the North it is often grown in the home gardens, but seldom in commercial plantations. The market demand is increasing.
The eggplant is an erect, branching, tender annual. The leaves are entire, oblong and grayish-green. The violet-colored flowers are solitary in the axils of the branches, shortly stalked and monopetalous; calyx often spiny, becoming larger as the fruit develops. The fruits are variable in shape, color and size, and are ready to use when one-third grown, continuing to be edible until fully mature. When the seeds begin to harden, the flesh loses its tenderness and delicious qualities. The fruits are usually sliced and fried.
There are three distinct colors of eggplants; namely, black, purple and white. Black-fruited varieties find most ready sale; purple-fruited sorts are attractive in appearance, but the smaller size of the specimens is objectionable from the market standpoint; white varieties are seldom seen on the market.
New York Improved is one of the most popular and largely grown of purple sorts. The fruits are large, well shaped and very attractive.
Black Beauty is an improvement over the New York Improved. The fruits ripen about 10 days earlier, are darker in color, and attain a size sufficient to satisfy market requirements.
Black Pekin has been grown commercially for many years, although it is not so popular in recent years as Black Beauty and New York Improved.
Early Long Purple is probably the earliest and hardiest of all varieties in cultivation. It is especially adapted to the cooler parts of the North, where the larger varieties do not succeed so well. The fruits are purple and 9 to 10 inches long.
Ivory is a white-fruited variety originated by Dr. B. D. Halstead of the New Jersey Experiment Station. The fruits are beautiful and nearly seedless. The white varieties are much more popular in Europe than in America.
On account of its extreme tenderness this vegetable is produced to best advantage in southern sections, because it requires higher temperatures than any other vegetable grown in the United States. Cool nights and short summers are very unfavorable to satisfactory yields. Because of the subtropical character of the plant, special care must be exercised in most sections to secure satisfactory results.
It is generally conceded that warm sandy soils are best adapted to eggplants. Good crops are seldom grown in clay soils except under the most favorable climatic conditions. It is important that the soil be deep, rich and well drained. A liberal amount of decaying vegetable matter is essential to the largest returns. Southern exposures should have the preference.
Only about 25 per cent of the eggplant seed used in the United States is imported, the seed being grown in the various sections where soil and climatic conditions are satisfactory. The saving of seeds is a simple matter. The fruits should be allowed to ripen thoroughly on the plants before removing the seeds. Separation and cleaning are readily effected by means of fermentation to loosen the pulp, followed by washing and screening.
In nearly all parts of the country, glass or other protection is given when starting the plants. In the North, the sowings are always made in greenhouses or hotbeds, while in the South, cloth or glass-covered cold frames are used, especially in starting early plants. The aim should be to grow a strong, stocky, hardened plant ready for the field at the desired time. In the North there are few sections where field planting should occur before June 1. To grow plants of the proper size by this date, the seeds need not be sown before March 10. Many successful growers prefer to sow later than this.
A temperature of not less than 65 degrees should be provided for germination, and from 65 to 75 should be maintained until the plants are set in the open ground. The seedlings require considerably more heat than tomatoes and somewhat more than peppers. If hotbeds are used it is often necessary to make up two beds, one for the germination of the seeds and the other for the care of the plants after they have been pricked from the seed bed. It is difficult to supply an excess of heat either in hotbeds or greenhouses. Too much care cannot be exercised to encourage a steady, unchecked growth. Stunting the plants at any period will cause the hardening of the tissues, resulting in a decreased yield of smaller fruits.
An excellent plan is to make several shifts. The plants may first be set in flats, the seedlings spaced 2 inches apart each way. Later they may be set in 3-inch pots, and finally transferred to 5 or 6-inch pots. When planted in the field there will be no check in growth and the fruits will ripen considerably earlier than if the plants are kept in flats or beds until planting time. More or less hardening before planting in the field is an advantage. About 120 to 160 days are required to produce a crop of eggplant.
Manure may be applied heavily for an early crop, like lettuce or radishes, to be followed by eggplants. While this vegetable will stand considerable drouth, there should be no lack of soil moisture if large fruits are desired. Early plowing and frequent harrowing are essential to secure proper conditions for planting.
Early growth and strong foliage are important. To accomplish these ends nitrogen must be supplied in quickly available forms. The organic sources are also important to meet the later demands of the plants. Before transplanting, the soil should receive not less than half a ton of a high-grade mixture, and just as soon as the plants are established a top-dressing of nitrate. The latter application should be repeated once or twice if necessary, to encourage vigorous growth. Thoroughly decayed stable manure can often be used to good advantage. Some growers apply it in the hill before setting the plants, but this is unnecessary in warm, rich soils.
Eggplants should never be set in the field until the ground is thoroughly warm. Many growers plant 3x4 feet apart, others 4x4 and some 2x3 feet. The vigor of the variety, climatic adaptability and the fertility of the soil are the main factors to consider when deciding upon distances. Four by 4 feet is not too much space when all conditions are advantageous.
The cultivation of the crop is a simple matter. Moisture conservation is important.
As the market demands rather large fruits, eggplants are not usually picked until full grown.
They stand shipment well, but should be handled with care so there will be no bruising. Wrapping in attractive paper containing the name and the address of the grower is an effective means of advertising. The paper gives some protection to the fruits during transportation. The yields are much heavier in the warmer sections where the summers are long. With fairly advantageous conditions two or three specimens to the plant will give a satisfactory return. The development of additional specimens is sometimes prevented by removing the flower buds or blossoms. Such restriction possesses the greatest value where both soil and climate are unfriendly to this extremely tender vegetable. Eggplants are shipped in barrels, hampers and crates. There should be careful grading in order that the largest profits may be realized.
This vegetable has a number of enemies which become sometimes serious. Potato beetles are very fond of the plants. It is 'often necessary to protect the plants from flea beetles, cut worms and aphides. There are various forms of fungous diseases which may be controlled by spraying with bordeaux mixture.