322 VEGETABLE FORCING 



ture with sunshine should be from 80 to 85 degrees, or 

 15 degrees higher than the night temperature. 



The temperature of the soil is a subject of interest 

 among greenhouse growers of cucumbers. This topic 

 was alluded to on page 302, in the discussion of ground 

 beds vs. raised benches. It will be recalled that cu- 

 cumbers are sometimes forced on raised benches. In 

 New England, hot horse manure is sometimes placed in 

 trenches in the greenhouse previous to setting potted 

 plants, where it has much the same effect as when used in 

 hotbeds. 



The higher soil temperature thus secured is regarded 

 as a decided advantage by some growers, especially for 

 the winter crop, and the additional fertility must also 

 have an influence on the growth of the plants. The in- 

 creased expense, however, involved in the employment of 

 this method should be carefully considered before one 

 decides to follow it. 



Moore of the Wisconsin Experiment Station conducted 

 experiments for three seasons to determine the influence 

 of bottom heat. Greenhouse benches, with various de- 

 grees of bottom heat, were employed. The results of 

 these studies are summarized as follows in the 24th 

 Annual Report of the Wisconsin station : 



"1. That a soil temperature of approximately 74 degrees gives 

 greater fruitfulness during the same length of time than tempera- 

 tures ranging either much higher or much lower. 



"2. That earliness of production is increased very little, if any, 

 by the increase in soil temperature. 



"3. That flower production is influenced only slightly, if any, 

 by various degrees of soil temperature. Sunshine, atmospheric 

 temperature, and individuality of plants are the important .factors 

 in this respect. 



"4. That higher soil temperature shortens the fruiting period 

 of the plants. 



"5. That the advantages gained by higher soil temperature would 

 not warrant the additional cost entailed in increasing it above that 



