CHAPTER 12 



LETTUCE {Lactuca sativa) 



Cultural Considerations. Lettuce is extensively 

 grown as a greenhouse crop (fig, 25). The best re- 

 sults are obtained where the soil contains consider- 

 able sand, especially where head lettuce is produced. 

 This is also true for Coss lettuce. However, the 

 Grand Rapids variety will thrive in any soil. Let- 

 tuce is a heavy feeder, hence stable manure is often 

 used exclusively. If the crop does not make rapid 

 headway, nitrate of soda at the rate of one pound 

 to 100 square feet of space may be applied. In 

 using acid phosphate or potash only small quantities 

 should be applied for fear of burning the plants. 

 Lettuce requires an abundance of water and good 

 drainage. High temperatures and humidity will 

 produce weak, spindly plants. Careful ventilation 

 may be the cause of preventing numerous diseases. 

 In mild weather the ventilators may remain open 

 even at night. This, however, should not be done 

 during freezing weather. 



It is fortunate that lettuce seed retains its vital- 

 ity for three or four years. This enables the grower 

 to test out carefully the strains which he uses. 



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