THE CULTURE OF SET ONIONS 7 



% inch to 1 inch are frequently used; when sets are plentiful, only the optimum 

 sizes are used. Notwithstanding the fact that large sets produce many bolters, 

 they are often planted because they mature early and the grower may take ad- 

 vantage of early-season prices. As set size increases, yield per acre also rises 

 (as shown in Table 2) ; but it should be borne in mind that when larger sets are 

 used the number of bushels required to plant an acre increases sharply (see 

 Table 5). 



It has been customary to spafee onion rows 12 to 13 inches apart. With the 

 advent of power machines for onion culture, it was found necessary to increase 

 the width between rows to at least 14 inches in order to prevent injury to roots 

 and tops and to better control weeds. Table 3 gives the yields of mature onions 

 from rows of varying widths. 



Table 3. — Effect of Varying The Distance Between Rows 

 ON Yields of Mature Onions. 



12 inches..- 615 - 



13 inches 630 740 



14 inches.... 569 600 



The usual practice is to plant the small sets 2J^ inches apart, measured center 

 to center, in the row. An experiment was conducted for three years to determine 

 the effect on yield of different spacing in the rows. While yields from close 

 spacing were much greater, the percentage of small bulbs ("picklers") was high 

 and the number of sets required per acre was large (Table 4), 



Table 4. — Effect of Spacing in The Row on Yield of Mature Bulbs. 

 Sets of J^" to %" size, spaced 13.8" between the rows. 



Spacing in Row 



Yield — 

 50 lb. Bags per -Acre 



1940 1941 1942 



Close, 13^" 740 680 810 



Normal, 2}i" 670 575 660 



Wide, 33^" 550 510 520 



Careful measurements of set sizes from random samplings were compiled in 

 Table 5 to show the approximate number of bushels of sets of different sizes re- 

 quired to plant an acre at varying distances apart between the rows and in the 

 row's. 



