FRUITS AND VEGETABLES UNDER GLASS 



Most Lettuce grown under glass is probably head Lettuce of the Boston 

 Market type. Some varieties of tliis are somewhat stronger growing than 

 others. May King, for instance, which does exceedingly well under glass, re- 

 quires to be planted nine inches apart each way, but for most other head Let- 

 tuce eight inches each way is about right. Have the beds moist when planting 

 or just in a friable condition. Where the loose-headed type is grown, such as 

 Grand Rapids, a space of ten inches each way may be allowed. Grand Rapids 

 will also thrive better in a somewhat heavier soil; at least, heavier heads can be 

 grown in such soil. There is apparently more demand for head Lettuce m the 

 \'icinity of New \'ork than for anything else. 



TEMPERATURES 



There may be a difference of opinion among growers as to temperatures 

 for Lettuce. Undoubtedly, if it is kept around 50° at night and correspond- 

 ingly high in the day, it will mature somewhat quicker. But Lettuce forced 

 to the extreme will be of poor grade, and the gain in time is offset by loss in 

 quality, color and weight. As it is the high grade article that is most in demand, 

 I cannot see the advantage of severe forcing, and I do not recommend it, for 

 several reasons. In the first place, the plants are more liable to go wrong, and in 

 the second place, few people want those soft, loose heads. Where Nature is 

 allowed to do her work, we find Lettuce in its full glory, that is, when the nights 

 are cool and the days around 60 . Then why advocate a warm night tem- 

 perature? When Lettuce is brought along in a comparatively low night tempera- 

 ture, particularly when it begins to head up, its progress will be rapid. This 

 is a clear enough indication that cool nights are agreeable both to the health 

 and the vigor of the plant. Each grower must, however, use his own best judg- 

 ment. When the weather is bright and clear, rather than have a setback, it 

 will do no harm to allow about 65°, with a fair amount of air on; but on a dark, 

 cloudy day tliis would be a serious error. I consider a reliable Lettuce tem- 

 perature about 40° to 45° by night, with a rise of 10 to 15 during the day, 

 according to the weather. 



Airing is an important factor in a successful Lettuce crop, for it is naturally 

 a fresh air plant, and cannot withstand a close, humid atmosphere. It is well 

 to leave a crack of air on both day and night, at least until the frost sets in. 

 Such treatment will make the plants more thrifty and less subject to disease. 

 Careless airing is one of the first causes of failure, for while Lettuce is not es- 

 pecially sensitive to cold blasts when growing in the open, it will not withstand 

 careless treatment under glass. The great secret of success is to grow it along 

 without a check, from the time the seed is sown until it is ready for cutting. 

 The result of careless airing is, a check and other troubles, as disease, green fly, 



