144 GREENHOUSES 



the placing of the heating pipes underneath, 

 which makes them less conspicious and at 

 the same time affords a method of giving 

 "bottom heat/' which is considered advant- 

 ageous with many plants. (3) It is main- 

 tained that there is a better circulation of 

 air about plants grown on benches and that 

 the plants are less subject to disease. (4) 

 The temperature and moisture of the soil 

 can be more easily regulated in benches. 

 (5) Low-growing plants make a better dis- 

 play when grown on benches. 



The following are the most common dis- 

 advantages claimed by those who urge 

 against the use of benches, (i) They are 

 expensive to build and maintain. (2) They 

 do not admit of an economical use of space. 

 (3) The soil dries out rapidly. (4) The soil 

 has to be changed more often. (5) It is 

 more difficult to use labor-saving tools such 

 as wheel-barrows. (6) All work must be 

 done by hand. In large houses it is possible, 

 when plants are grown on the ground, to pre- 

 pare the soil with a horse or with wheel hoes. 

 (7) With high-growing plants such as to- 

 matoes and cucumbers, it is difficult to har- 

 vest the crop when they are grown on high 

 benches. 



