Propagation.—It is always grown from seeds, which are small and light; half an ounce being sufficient to sow a nursery-bed of nearly a hundred square feet. It is necessary that the ground should be well pulverized and made smooth before it is sown, and the seeds should not be covered more than a fourth of an inch deep.
Cultivation.—Some recommend sowing where the plants are to remain, in drills from ten to fifteen inches apart, and thinning the plants to nearly the same distance in the lines; adapting the spaces between the drills, as well as between the plants in the drills, to the habit and size of the variety in cultivation. Others recommend sowing in a small nursery-bed, and transplanting. The process of transplanting unquestionably lessens the liability of the plants to run to seed, and produces the largest and finest heads. The first sowing in the open ground may be made as soon in March or April as the frost leaves the ground; and, if a continued supply is desired, a sowing should afterwards be made, at intervals of about four weeks, until September. "During spring, the young crops must be protected from frost, and in summer from drought by copious manure-waterings and frequent stirring of the ground between the plants. In the growing season, every stimulant should be applied; for much of the excellence of the crop depends on the quickness of its growth."
Forcing.—Lettuce is now served at table the year round; not, of course, of equal excellence at all seasons. Sowings are consequently required for each month: those intended for the spring supply being made from December to February; about twelve weeks being required for its full development, when reared in the winter months. The seed is sown rather thinly, broadcast, in a hot-bed; and, when the plants have made two or three leaves, they are pricked out to three or four inches apart in another portion of the bed,—thus affording them more space for growth, and opportunity to acquire strength and hardiness. When two or three inches high, they are finally transplanted into yet another part of the bed, at distances corresponding with the size of the variety, varying from ten to fourteen inches in each direction. As the plants increase in size, the quantity of air should be increased; and water should be given, whenever the surface of the bed becomes dry. In severe cold or in cloudy weather, and almost always at night, straw matting (made thick and heavy for the purpose), woollen carpeting, or a similar substitute, should be extended over the glass, for the retention of heat.
Some practise transplanting directly from the nursery-bed to where the plants are to remain; but the finest Lettuce is generally obtained by the treatment above described.
"Lettuces are sometimes required for cutting young, or when about two inches high. These are termed, by the French, Laitues à couper. The small, early sorts (such as the Hardy Hammersmith and Black-seeded Gotte) are preferred for this purpose; but any sort that is green or pale-green, and not brown or otherwise colored, will do. They should be sown in the open ground about once a week, or every ten days, from April, throughout the season. In winter, they are best raised on heat. They should be sown rather thickly in drills six inches apart."—Thomp.
To save Seed.—"This should be done from plants raised from early sowings. The finest specimens should be selected; avoiding, however, those that show a disposition to run quickly to seed. Those that heart readily, and yet are slow to run up, are to be preferred. Care should be taken that no two different varieties be allowed to seed near each other, in order that the sorts may be kept true. The seed which ripens first on the plant is the best: therefore it should be secured, rather than wait for the general ripening. The branchlets which first ripen their seed should be cut off, and laid on a cloth in the sun; or, when the forward portion of the seed is as near maturity as will safely bear without shaking off, the plants should be carefully pulled up, and placed upright against a south wall, with a cloth under them to perfect their ripening. The seed should in no case be depended on without trial. Plants from seeds two years old heart more readily than those from one-year-old seed."—Thomp.
Use.—"Lettuce is well known as one of the best of all salad plants. It is eaten raw in French salads, with cream, oil, vinegar, salt, and hard-boiled eggs. It is also eaten by many with sugar and vinegar; and some prefer it with vinegar alone. It is excellent when stewed, and forms an important ingredient in most vegetable soups. It is eaten at almost all meals by the French; by the English after dinner, if not served as adjuncts to dishes during the repast; and by many even at supper. In lobster and chicken salads, it is indispensable; and some of the varieties furnish a beautiful garnish for either fish, flesh, or fowl.
"In a raw state, Lettuce is emollient, cooling, and in some degree laxative and aperient, easy of digestion, but containing no nourishment."
Varieties.—These are exceedingly numerous. Some are of English origin; many are French and German; but comparatively few are American. The number of kinds grown to any considerable extent in this country is quite limited. Cultivators generally select such as appear to be best adapted to the soil and climate of their particular locality; and, by judicious management, endeavor to give vigor and hardiness to the plants, and to increase the size, compactness, and crispy quality of the head. Some of the varieties have thus been brought to a remarkable degree of perfection; the plants producing heads with as much certainty, and nearly as well proportioned and solid, as those of the Common Cabbage. They are generally divided into two classes; viz., Cabbage lettuces and Cos lettuces.
Cabbage Lettuces.—