360 The Principles of Vegetable -Gardeiii^ig 



apply nitrate of soda soon after the plants are set. The 

 nitrate is usually sprinkled broadcast on the surface and 

 raked or cultivated in. An application at the rate of 

 200-300 pounds to the acre may be made with o:ood 

 results. The surface of the ground should be kept well 

 tilled in order to conserve the moisture and to promote 

 all those activities which result in quick growth. 



Lettuce is commonly grown in rows 8-12 inches apart, and 

 thinned eventually, as the young plants are taken out, to 6-12 

 inches apart in the row. For early use, start in forcing-house, 

 frame or kitchen. Sow in succession till warm weather. Calcu- 

 late on 1,000 plants for each ounce of seed. Most of the forcing 

 varieties, started under glass, are good for early use, as Tennisball, 

 Boston Market, Simpson. For summer use, plant varieties that 

 withstand the heat, as Deacon, Hanson, Summer Cabbage, Cos. 



Lettuce {Lactuca saiiva) is probably native to Europe and 

 Asia, although its wild prototype is not definitely known. By some 

 it is supposed to have descended from Lactuca Scariola, a tall homely 

 plant that has now become a weed in many parts of the country. 

 There are four well-marked tribes or races, — head lettuce, cut- or 

 curled-leaved, Cos, and narrow- leaved. The last is little known 

 to gardeners. Goff (in 4th Rept. N. Y. State Exp. Sta., pp. 156-202) 

 reduces the varieties to 87. His classification is as follows: 



A. Leaves roundish or but slightly oblong, spreading. 

 B. Borders of leaves plain or nearly so. 

 c. Foliage green, 

 cc. Foliage more or less tinged or spotted with 

 red, brown, or purple. 

 BB. Borders of leaves ruffled. 



(Color divisions as above.) 

 AA. Leaves oblong, tending to grow upright. 

 B. Leaves oval or spatulate. 



(Color divisions as above.) 

 BB. Leaves lanceolate. 

 AAA. Leaves pinnately lobed. 



