CULTIVATION. 67 



temperature of 16° C. — or a total amount of heat equivalent 

 to 2928° C. during the summer months — a deep, mild soil 

 and sufficient moisture, the successful cultivation of the hop 

 becomes a certainty. 



Schoffl asserts that hops may be grown wherever lucerne 

 will thrive, and that districts where the temperature of the 

 ground in June and July does not vary beyond the limits 

 of 10° C. on the one hand and 15° C. on the other are the most 

 suitable for hop cultivation. It must, however, be borne in 

 mind that only the coarser varieties of hops will do well in 

 cooler climates, it being impossible to grow fine red hops in 

 cold districts. The hop cannot stand sharp and oft-repeated 

 fluctuations of temperature, their occurrence invariably re- 

 sulting in evil consequences ; and any district subject to 

 marked contrasts of heat and cold must be considered as 

 fundamentally unadapted for hop-growing. 



The hop plant develops most satisfactorily when the tem- 

 perature rises slowly and constantly from the first awaken- 

 ing of vegetation up to the month of August, and then 

 gradually and uniformly recedes. Low temperatures are of 

 no infrequent occurrence during the early stages of growth, 

 frosts in April and May being far from uncommon. These, 

 however, even when they produce torpidity in the young 

 shoots recently emerged from the ground, do not cause so 

 much damage as sharp depressions of temperature — even 

 though not as low as freezing point — in June and July. 



If the frozen young shoots thaw out again slowly they 

 resume their faculties uninjured. On the other hand, if they 

 are killed, which happens when thawing is effected suddenly, 

 the damage, when recurring in April while the shoots are 

 still small, is not very great so far as the loss of material is 

 concerned, because new shoots soon spring up and develop 

 normally. May frosts are more injurious than those of April, 

 since, if the now strong bine is killed by cold, the new shoots 



