140 PBINCIPLES OF PLANT CULTURE 



plants grown in winter on poorly-lighted benches are 

 often unfruitful even when they grow well and bloom 

 freely. Such plants, though of species that normally 

 grow upright, are often unable to stand erect without 

 support. Familiar examples are cabbage and tomato 

 plants that lop over when planted out, because grown in 

 the seed-box to transplanting size without " pricking 

 off " (105) ; and grain sown too thickly on rich ground, 

 that falls (lodges) before maturity. 



238. Close planting. — Too close planting causes de- 

 ficient light and all the resulting evils. Indian corn grown 

 too thickly does not ear well and is lacking in nutritive 

 qualities ; strawberry plants grown too closely do not 

 fruit well and the fruit lacks flavor and firmness ; nursery 

 trees grown too closely are slender-stemmed, deficient 

 in foliage and have poorly developed roots. A rule to 

 govern distance in planting has already been given (122). 



When a slender and flexible growth is desired, as in 

 trees grown for hoop poles, or willows for wicker-work 

 and tying, a certain amount of crowding is advisable. 



239. Weeds cause deficient light in low-growing crops, 

 such as strawberries, dwarf beans, potatoes and the like, 

 and also tend to rob the plants of food and moisture. 

 They are, therefore, decidedly injurious (336). 



240. Plants under glass are especially liable to suffer 

 from deficient light, because the walls and sash-bars of 

 the structure necessarily intercept a considerable part 

 of the solar rays. The roofs of glass-houses should be 

 formed of large lights of glass, with the smallest possible 

 sash-bars, and the benches should be arranged to bring 

 the plants as near to the glass as possible. 



Plants having their leaves densely covered with hairs 

 generally require a large amount of light. 



