GROWING EARLY VEGETABLE PLANTS UNDER GLASS 159 



off the mats by taking hold of the lapped-over ends. If 

 wet, they should be spread flat on the ground or, better 

 stiir, supported on a fence to facilitate drying. To cover 

 the frames in the evening when the mats are wet, proceed 

 as follows : Walk on the mat, reach backward, grasp the 

 far end with both hands, walk over the frame at a cross- 

 bar and drop the mat in place. When dry, they are 

 handled rapidly and with ease. 



Mats are also useful in shading plants. The glass may 

 be covered entirely in hot weather, or the opposite edges 

 of the mat may be turned back, exposing 6 to 12 inches 

 of glass along each side of the frame. This method of 

 shading is especially valuable when transplanting is done 

 late in the spring. 



219. Hardening plants. — This process is the firming of 

 the tissues in order that the plants will be able to endure 

 the hardships of transplanting and of open-ground condi- 

 tions such as freezing, hard drying winds or hot sunshine, 

 any of which may damage or destroy soft, tender plants. 

 Figure 42 shows a frame of well-hardened cabbage plants 

 which when photographed were of reddish-blue color, 

 short and stocky. Such plants will stand a tempera- 

 ture of 12 or 15 degrees above zero. 



Plants are hardened by watering sparingly, subjecting 

 them to low temperatures and by providing free ventila- 

 tion. These operations are equally valuable. When 

 hardening is begun, no more water should be used than 

 is necessary to prevent serious wilting. Air is admitted 

 more freely from day to day. At the end of three or four 

 days the sash may be removed entirely during the day, 

 and the frames closed late in the evening and opened ear- 

 lier than usual the next morning. Matting is not prac- 

 ticed after a few days more of such treatment and, finally, 

 no protection of any kind is given day or night. This 

 general plan of hardening is primarily for the more hardy 

 plants, as cabbage and lettuce. Tomatoes, peppers and 



