234 Gardening 
Fic. 132. When onions are about two- 
thirds grown, the tops are sometimes 
broken down, as shown in this picture. 
By this practice the growth of seed tops 
is checked, the size of the bulb is increased, 
and hollow centers are not so likely to form 
within the bulb. 
these buibs may be used 
as food until late in 
the following spring. If 
these one-year-old bulbs 
are planted in spring, 
they produce tall stalks 
bearing flowers, and 
later, seeds; then the 
mother bulb dies. Seed 
is thus produced in the 
second year of the plant’s 
growth, and for this 
reason the onion is a 
biennial. 
If, however, the seeds 
are sown late, or the 
young plants are much 
crowded, or are grown 
on poor soil, the plants 
do not form large bulbs 
that year. Instead, the 
tops die in summer, 
leaving only small bulbs 
that are called “ sets.” 
If these sets are planted 
early in the following 
spring in rich soil with sufficient room, the plants 
grown from them will make large “dry” bulbs. 
‘These, if stored through the winter and planted the fol- 
lowing season, will produce seed. Sets are therefore 
plants that are halfway to the dry onion stage of de- 
