306 STORAGE OF VEGETABLES FOR WINTER USE 



contact with circulating air. Cabbage may be successfully stored 

 under the same conditions. Onions must be kept at a low tem- 

 perature, but differ from the root crops in that they must be in a 

 dry atmosphere and have free circulation of air. In a moist 

 atmosphere, under high temperature, they would either rot or 

 sprout. Vegetables that are expected to continue growth while 

 in storage, such as celery, leeks, Brussels sprouts, and parsley, 

 must be planted in dirt and the roots kept moist. Air should 

 circulate freely about the tops, and the temperature must be low. 

 On the other hand, sweet potatoes, pumpkins, and squashes 

 demand a high temperature and dry atmosphere, with free circula- 

 tion of air. 



The conditions of storage favorable to the different crops are 

 secured in various ways. Market gardeners use outdoor pits or 

 specially constructed cellars for their root crops, cabbage and 

 celery. Onions are commercially stored in slatted crates piled in 

 tiers in frost-proof houses provided with means for ventilation 

 so that the temperature can be maintained at slightly above 

 freezing. Sweet potatoes and squashes are also stored in specially 

 constructed houses, in which the temperature can be controlled; 

 but since a high temperature is demanded for these crops, artificial 

 heat is usually employed. Circulation of air about these prod- 

 ucts in storage is faciUtated by the use of slatted bins, and 

 allowing ample space between the bins and the side walls of the 

 building. 



VEGETABLE STORAGE HOUSES 



In the construction of vegetable cellars and storage houses, 

 protection against frost is provided in various ways. Outdoor 

 cellars used for the storage of potatoes, celery, cabbage or root 

 crops in cold climates are usually made partly under ground, 

 and the roof is supported by heavy timbers and covered deeply 

 with earth (Fig. 183). Usually this is sodded to prevent washing 

 by heavy rains. Storage houses for onions, sweet potatoes (Fig. 

 184) and squashes are usually built entirely above ground, and the 

 walls insulated to prevent fluctuations in temperature. The air 

 in a storage house above ground can be kept drier than that in one 

 below; hence the use of above-ground houses for these products. 

 The insulation may consist of a series of dead-air spaces in the 

 wall, made by using layer after layer of building paper, separated 

 by wooden strips from one to four inches wide, until a wall twelve 



