242 VEGETABLE FORCING 



copiously with a hose, care being taken not to wet the 

 heads or the foliage, and special fertilization may also be 

 given at this period. Previous to the formation of heads 

 there is no objection to applying water as a spray. 



A moist atmosphere at all times is favorable to. the 

 growth of cauliflower. In warm, sunny weather it is of 

 advantage to sprinkle the walks with water in order to 

 increase the humidity in the house. 



Temperature. While cauliflower is often grown under 

 glass with lettuce and radishes, it thrives best at some- 

 what higher temperatures than are required for these 

 crops. The temperature at night may be 50 to 55 degrees, 

 and by day 65 to 70 degrees, though good crops are often 

 grown with less heat. 



Ventilation. Ventilation is essential to the growth of 

 healthy plants and to the formation of good heads, but 

 cauliflower is very sensitive to cold drafts, which may 

 cause the leaves to droop and prevent head formation. 

 Some fresh air should be admitted to the houses daily, 

 but cold drafts should never strike the plants. 



Cultivating. The beds of cauliflower should be cul- 

 tivated at frequent intervals. This is of special value in 

 conserving soil moisture and in encouraging the most 

 satisfactory growth. One of the chief objections to inter- 

 crops of lettuce or radishes is that they interfere to some 

 extent with thorough cultivation. 



Insect enemies. The green aphis is the most serious 

 pest of cauliflower grown under glass, but it is easily 

 controlled by tobacco fumigation. (See page 105.) The 

 larvae of the cabbage butterfly sometimes feed on plants 

 started during the fall months. Arsenate of lead, or, if 

 preferred, fresh pyrethrum or insect powder, may be used 

 to poison this pest. 



Diseases. Cauliflower is subject to the same diseases 

 as cabbage and other brassicae. The commonest are 

 soft rot or stem rot, black rot and club root. They sel- 



