FRAME CROPS 



393 



Mats and shutters. In very cold weather, sash alone 

 will not keep frost out of the frames ; additional protec- 

 tion, therefore, is necessary at times. Probably no other 

 covering is more effective in guarding against cold than 

 rye straw mats (Fig. 134), though the sea grass mats, 

 seen in Fig. 135, are most excellent. If better protection 

 is required, board shutters placed over the mats and 

 manure banked around the outside of the frames will 

 take care of the plants when the weather is very cold. 

 Growers in .the coldest parts of the North, who use 

 various methods of heating the frames, often employ mats 



Fig. 135. Frame cauliflower following a companion crop of lettuce. Note mats 

 which are being thoroughly dried before they are stored for the summer. 



and occasionally shutters to conserve the heat. It is not 

 uncommon to see both mats and shutters on steam-heated 

 frames during the daytime, when there are high winds 

 and extremely low temperatures. 



Heating frames. It is impossible to give any rule for 

 the heating of frames. Thousands of frames are used 

 without any artificial heating. In the South, the muslin 

 or sash-covered frames will keep the plants growing 

 throughout the winter. In the North, they may give the 

 necessary winter protection to certain crops, and rapid 



