404 



VEGETABLE FORCING 



hundreds of frames in which lettuce is grown are heated 

 by steam or hot water. 



Big Boston is the main forcing variety, especially in 

 the Atlantic coast states. It is extremely hardy and will 

 stand a large amount of exposure without serious injury. 

 All of the varieties mentioned on page 207 are also grown 

 to some extent in frames. 



Seed for the fall crop is generally sown from August 15 

 to 20. If the plants for the spring crop are to be wintered 

 in the frames, the seed should be sown about October 1 

 in the South, and the plants set in the frames later in the 

 fall and covered with sash or muslin. In the North the 



Fig. 145. Choice heads of lettuce saved for the production of seed. 



plants may be wintered in the frames or started in hot- 

 beds or greenhouses in January or February, and then 

 set in the frames in March, or even as late as April 1. 

 The date of sowing and transplanting may depend largely 

 on the uses of the sash and frames for other crops. Big 

 Boston is set at various distances, probably 9 by 10 inches 

 apart being the average. 



Muskmelons may be grown in frames by the same 



