food. In like manner, tree leaves and other organic materials are well pre- 

 served and therefore accumulate more in northern New Hampshire and in 

 the highlands than in southern New Hampshire lowlands. 



Growing Season 



Each plant has its own I'equirement regarding the number of days neces- 

 sary to mature. Corn, for example, requires 80-120 days, depending upon 

 the variety. Plant breeding has developed quickly maturing varieties of 

 corn, tomatoes, watermelons, muskmelons and manv other crops which are 

 adapted to the short growing seasons found in New Hampshire. While 

 plant breeding has made rapid progress, there is a limit beyond which 

 certain plants cannot be adapted to the short growing season in various 

 parts of New Hampshire. 



The length of the growing season is shown in Figure 5 as an average 

 number of days without killing frosts. The growing season averages 100 

 days in the northern part to 140 days in the southern part of the State. 



The average last killing frost in the spring shown in Figure 6 deter- 

 mines the best planting dates. The map shows the last killing frost to be 

 June 10 north of the White Mountains and May 20 in the southern lowlands. 



As a general rule it is best to plant such crops as corn approximately 

 the time of the average last killing frost in the spring. This means that in 

 southern New Hampshire, May 20 is a desirable date for planting corn. 





1941 Yearbook of Agriculture 



Figure 3, at tlie left, shows the average .Tanuary temperatures m New Hamp- 

 shire, while Figure 4, at the right, recort'^ the average July temperatures. 



12 



