17 



thorough cleaning. The glass in a cucumber house should be cleaned 

 every year or two, especially if crops are to be grown between Novem- 

 ber and February. With a thorough cleaning of the glass occa- 

 sionally, there is no reason why the deterioration should exceed 5 to 

 8 per cent at the end of five years. 



Among cucumber growers in certain localities of the State there is 

 and has been for many years a practice of double roofing as a means 

 of keeping out the cold and economizing in fuel. In this method of 

 construction, pieces of moulding are fastened to the inside of 

 the sash bars which constitute the roof and sides of the house, 

 these holding in place a second layer of glass. This forms a 

 double roof and sides to the house, with a i^V or 2 inch air space 

 between. Some constructors do not carry the double roofing to the 

 ridge, but stop about one-half or two-thirds of the way up, thus 

 leaving the upper part of the roof near the ridge with a single layer 

 of glass, while the lower part is provided with two layers. Certain 

 growers who make use of this plan maintain that it is impossible 

 to grow plants in any other way, while others can not be induced to 

 use it. We have observed a great many crops of cucumbers grown 

 under both of these methods of construction with marked differences 

 in results. The objection to the double roof system is the collection 

 of moisture and dust which shuts out the light, and we have observed 

 more than once houses constructed in this manner which itwas almost 

 impossible to see through. The double roof system is also costly, 

 the glass becomes more readily corroded, and, while it may keep out 

 a certain amount of cold, the advantage is, according to our obser- 

 vation, not so great as that which would result from differences in 

 exposure or from the use of an economical boiler. Cucumbers are 

 especially susceptible to light and even under the most favorable 

 conditions in our latitude they not infrequently suffer from the want 

 of it during the winter months. From the first of November to 

 the first of February they should receive all the light possible, 

 not only for their foliage, but for their fruit ; and any method 

 in the construction of greenhouses for cucumbers which fails 

 to take this factor into consideration is radically wrong. We have 

 seen many instances in double glass houses where the plants were 

 unhealthy from the lack of light (cf. wilting p. 32). Such plants 

 not infrequently show symptoms of partial etiolation, or, in other 

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