Of all salad plants, lettuce is probably the most universally popular. It is rarely used for any other purpose than for salads. Its cultivation may be carried on by means of hotbeds, cold frames, and the open ground throughout the whole year. The greatest demand for it is in the spring when the appetite craves something fresh and succulent. Seeds are frequently started under glass in February or March and the seedlings transplanted into the flats, and placed in cold frames for hardening off so as to be transplanted to the open ground as soon as the spring opens. Successions may be made by sowing seed in the open ground at the time when seedlings are transplanted and at intervals of ten days thereafter until May.
For home use, it is essential that only a small area be planted at a time, because the plants quickly run to seed in hot weather, and as soon as the seed stalk begins to grow the leaves become too bitter to be relished as salad. Frequently lettuce is grown between rows and plants of early cabbage and cauliflower, so as to occupy the space and thus get two crops off the same land with almost no additional work. The lettuce is removed long before the other crop needs the ground. Plants should not stand closer together than 4 inches in the row. It is customary, in home gardens, to sow rather thinly, and to thin out the little plants when they are about 2 inches high, using the thinnings for a first salad and leaving the plants about 2 inches apart for about two weeks until they begin to crowd again, then removing each alternate one. Like all crops grown for their leaves lettuce needs abundant nitrogenous food in the soil and will respond well and quickly to light surface dressings of nitrate of soda.
There are several classes of lettuce, the principal of which are heading, cutting, and cos. The heading varieties form heads resembling cabbage. The cutting sorts do not form heads. They have loose leaves. The cos varieties are especially adapted to withstand hot weather; they produce elongated heads of very superior quality. Then there are special varieties in each of the first two classes adapted for forcing and for outdoor planting, Among the best known heading varieties are White Tennis Ball (or Boston Market), Hanson, and Black-Seeded Tennis Ball. Among the cutting varieties are Black-Seeded Simpson and Grand Rapids. For summer use Salamander is a good heading sort. All of the cos varieties are good.
George Tong of Hennepin county, Minnesota, grows head lettuce in hotbeds as follows: ” Plants were started about March in an ordinary hotbed and were well aired to get hardy plants. The hotbed into which they were transplanted was made the last week in March, making a bed of hot manure 8 feet wide and 18 inches deep on top of the ground. Frames were made as for ordinary cold frames, except that they were deeper, 18 inches back and 10 inches front.
“These frames were set on the manure. After the mass had settled well and had been trampled evenly 5 inches of rich soil was put on. This was covered with about 1 inch f rotted sheep manure and thoroughly mixed with the soil. The bed was then marked so plants would stand 8 inches each way, putting in about 40 plants to the sash.
“Our sashes are made 3 x 6 feet, using 2 x 2-inch stuff, with a crossbar of the same in the middle.
Common sheeting, costing 8 cents a yard, was tacked on this frame with large headed tacks. Plants were set out the last day of March, and it seemed as if to test the value of the plan a cold snap came; on the morning of April 2 the thermometer stood at 16 degrees above zero. Cabbage and cauliflower plants set in a well-protected cold frame were frozen badly, while this bed, with only a slight protection of wild hay, came through without a bit of frost.
” The sashes were removed every day, unless Tt snowed or the thermometer stood below 40 degrees, but were covered every night where there was danger of frost. Scarlet Globe radishes were sown between each pair of rows, and were sold at a good profit ten days before we could pull from outdoors. A few sashes were planted to Grand Rapids lettuce, which was ready to cut May 20, while plants set outdoors were not ready until two weeks later.
” In 1886 Peter Henderson wrote that he had never seen cos lettuce in the markets. Now there is not a day during the season when it is absent, and there is not a first-class city restaurant that considers its menu complete without romaine, as the class is popularly known. This is due solely to the merits of the varieties which have long been justly popular in home gardens. They are more tender and more crisp than ordinary lettuces, and have more elongated heads, being usually conical, and from 8 to 10 inches high and 5 or 6 inches in diameter.
Like other varieties of lettuce, the seed may be sown in hotbeds or cold frames, or in the open ground, either for transplanting or thinning where sown. The soil should be well supplied with humus and nitrogenous plant food. Most of the varieties are improved by having the outer leaves drawn together and tied Ioosely over the head, but some varieties are said to be compact enough to render this tying unnecessary. It is characteristic of the cos varieties to become annual residents in the gardens of those who give them a trial.
” Lettuce is easy to grow. For first early I would make a bed in the fall and cover it with about one-half inch of well-rotted manure. About February 1 I sow the seed broadcast, not too thick, and draw the back of the rake over it just to hide the seeds from the birds. If sown in rows and covered with soil the seed will not likely come up. One great hindrance in getting good lettuce is sowing seed too thickly. By transplanting some good plants, about the first dry spell in April or later, and about 5 or 6 inches each way, and cultivating, I get fine lettuce. The best kind is a matter of choice. I have had the best success with the Grand Rapids, but it is not a head lettuce.”
“Last season, under rather unfavorable conditions, I grew some f the finest lettuce I have ever seen,” writes John E. Vail of Decatur county, Iowa. ” This was secured by using rectangular troughs in 16-foot lengths about 24 inches at the base and 18 inches high and wide at the top. They were covered with cheesecloth so arranged that it could be quickly lifted from the rows. This method gave most marked results over open air growth. It is cheaply applied and will hasten the development seven to 20 days.”
LETTUCE GROWING UNDER GLASS
” A greenhouse and a system of cold frames in some well-sheltered place will be found a profitable investment, the area of glass subject to circumstances. My experience for some years,” writes Frank S. Miller of Franklin county, Ohio, ” has been with a forcing house or houses of 10,000 square feet and 400 cold frame sashes 3 x 6 feet. The forcing houses are used exclusively for vegetables. About September 1 lettuce is sown in one of the cold frames and transplanted 1 x 2 inches apart. As soon as it has become well established with good fibrous roots, it is transferred to the forcing house, having been previously fertilized with well-decomposed manure, or, in its absence, fresh horse manure, spread evenly over the bed, which is then given a good watering. Either turned under carefully has given satisfactory results, and will serve for two crops. The distance apart in permanent beds is 8 x 8 inches.
” The best variety for winter forcing, in my experience, is Grand Rapids. If possible, never let the plants wilt after setting in permanent beds. After 48 hours root formation will have commenced. Afterward water freely. As soon as the surface soil is in proper condition loosen it up well, as a fine, well-pulverized soil prevents rot and also lengthens the intervals several days between watering.
“Supposing the gardener to keep on hand a constant supply of young plants, repeat the above program until the house is full. In five or six weeks the first planting should be ready for market. As soon as a bed or portion of a bed is cut, work the soil over and replant. Three crops can be grown, making the returns from a house very remunerative. We use Grand Rapids, a hardy and satisfactory variety, in preference to head lettuce. The latter kinds are more susceptible to rot, and, unless conditions are favorable, do not always head well. This in brief is the system practiced by most growers in the vicinity of Columbus.”