290 CULTIVATION OF VINES IN GREENHOUSES. 



be shortened as opportunities offer. It is unnecessary to enter 

 furtlicr into this department of the sulyecf , as the summer prunin<^ 

 and tlie preparation of young vines for different plans of training 

 are generally understood by gardeners. 



Thinning and Pruning the Grapes. 



Thinning should commence as soon as the grapes are the size of 

 peas. They should be thinned so as not to press too much against 

 each other when ripe. If not sufficiently thinned they will not 

 swell properly, and many of them will rot, especially if a damp 

 season. The great secret in preserving grapes is to keep the house 

 thoroughly dry and as cool as possible, so that frost is excluded ; 

 therefore give air abundantly. In no case should artificial heat 

 be applied when the house is shut, unless during severe frost and 

 the roof of the house unprotected. It is evident that the more 

 heat is introduced to the house the more rapid is the ascent of 

 moisture from the lower to the upper parts of the house ; and as 

 heat and moisture are the chief agents in decomposition, the 

 conmion method of applying artificial heat when the house is shut 

 for the purpose of preserving grapes only hastens their decay. 



It is not to be expected that so large a crop of grapes can be 

 obtained from a greenhouse as from a late vinehouse pruned on 

 the long system ; but if the system is pursued which I have re- 

 commended, the produce of grapes in a greenhouse will be supe- 

 rior to a vinehouse of the same extent whose management is 

 conducted without regard to the recent improvements in horti- 

 cultural science. 



