CULTURAL DIRECTIONS 
395 
performed at the first weeding - , when 8 or io plants are 
allowed to the linear foot of row, but in very good soils 
and when large bulbs are desired, the plants should 
stand about 2 inches apart. Special hand weeders (Fig- 
ure 7) are in common use. Both weeding and thinning 
should be avoided as much as possible by the proper 
preparation of the soil and the adjustment of drills. 
Figure 92 shows a well-managed onion field on Long 
Island. 
FIG. 92. FIELD OF ONIONS ON LONG ISLAND 
539. Irrigation. — In many sections of the West and the 
Southwest onions cannot be grown without irrigation, 
the ground being too dry to supply the moisture neceS' 
sary. All of the Bermuda onions of the Southwest are 
grown under irrigation. The land is flooded before 
planting and afterwards at intervals of a week or 10 
days until the bulbs are full sized, when water is with- 
held to induce ripening. An increasing number of grow* 
ers in various parts of the country are employing the 
overhead system of irrigation, which is ideal when ap- 
