LETTUCE (the bartara swim, or garden lettuce) is one of the principal kinds of vegetables used for salads, and it also forms an ingredient in several kinds of soup. It has been introduced and culti vated in this country for nearly three centuries, but, like many other domesticated plants, its origin is unknown. The names of several of its varieties indicate their having come to us from the Greek Archipelago and the coast of the ]avant; and one of the two divisions into which the numerous varieties of lettuces are usually classed, termed Cos lettuces, derives its name from the island of Cos, the modern Stance. This division includes those of an erect oblong form of growth. The other division, which comprehends those of a roundish, flattened, or spreading form, is termed that of Cat &age lett aces.
The excellence of lettuces consists in their being crisp and tender ; their growth should therefore be so conducted as to sustain no check or interruption. If their quick vegetation be stopped by such causes as excessive drought, over-crowding in the seed-bed, or improper transplanting, they will in consequence either run to seed or be come tough, and their juices at the same time will acquire an acrid quality.
The ground intended for the seed should be fresh dug, rich, and mellow. The principal summer crop should be sown in March and April, and the seed lightly covered. A seed bed 4 ft. by 10 ft. will re quire a quarter of an ounce of seed, which ought to produce about 400 plants. If the plants are intended to attain their full perfection where sown, they must be thinned out to distances of 9 inches square, in the case of the small cabbage varieties, and the larger sorts should be allowed at least a foot each way. In transplanting, the above distances are likewise applicable and the operation should be performed, if possible, in cloudy weather; but at all events it must be done before the plants are too old or are in the least over-crowded ; for when they are drawn, or their stems have once commenced lengthening, which, in dry weather, will sometimes happen whilst they are yet in a small state, it is under* to transplant them. It is of importance that the soil in which they are grown be neither too wet nor too dry. Where the breadth to be planted is not so great as to render the expellee of labour an object of consideration, instead of making holes for the plants with a dipper, it is better to form a small trench, with a perpendieuler cut next the line, against which the roots are to be disposed without bruising.
Water should be given, but not at any one time to excess; nor merely at the root of each plant, but over the whole of the ground.
The Cos lettuces require to have their leaves tied together moderately close, with a strip of matting, for the purpose of assisting their blanch ing and rendering them more crisp and delicate. This should be done about a week previous to their attaining full perfection. The Paris Cove Cos requires least assistance in this way, because the tops of its leaves are concave, and successively apply themselves closely to each other. To obtain a constant supply, successive sowings are requisite to be made from February to July for the summer crop. Those plants intended to stand the winter should be sown in the end of August or beginning of September ; and when fit, should be trans planted to the bottom of walls or other fences having a south aspect, or to the sides of slopes or ridges, made for the purpose, over which a protection of mats, supported on hoops, may be formed. When the demand is such as to require greater security, recourse must be had to frames or pits. The first full supply from the open ground is best obtained by sowing under glass on a decayed hot-bed in the second week in October. When the plants come up they should be regularly thinned. Abundance of air should be admitted when the state of the weather will permit, and when mild the plants should be fully ex posed ; but the slightest frost should be guarded against. Very little water will be required ; in fact the effects of damp are to be dreaded, and therefore every favourable opportunity should be taken for the admission of air, provided it is not saturated with moisture, unless when too low a temperature would render such a proceeding inju dicious. A full exposure to air, both night and day, is necessary for some time previous to planting out in the open ground, which operation may take place in February, if the weather then prove favour able. A reserve should be kept in the frames in case of severe frost occurring after the plantation has been made.