112 VEGETABLE GARDENING 



quite early in the afternoon, and the covering put on to 

 retain the heat as soon as the sun is low. In the warm 

 weather of later spring, the sash of the hotbeds and frames 

 may be removed in the day and kept on only at night. No 

 exact rules can be laid down for ventilating, but it is quite 

 a simple matter to learn if one is observant and uses con- 

 stant vigilance. Many persons just beginning to use green- 

 houses and hotbeds fail to get best results from them because 

 they neglect the matter of ventilation. On cloudy morn- 

 ings it may not be needed, but if the sun comes through the 

 clouds it may warm the house or the beds in a very short 

 time, so that when they are examined the whole crop has 

 been injured by the heat. This is a most common cause of 

 failure by amateurs in charge of greenhouses and hotbeds. 



In nature the night temperature in which plants grow 

 averages from fifteen to twenty degrees below that of the 

 day, and it has been found in practice that when this con- 

 dition is reversed the plants do not do well. This, of 

 course, can be easily avoided by a little forethought. It is 

 a bad plan, generally speaking, to ventilate much in cold 

 weather when the leaves are wet. On this account it is 

 best to water early in the day, so that the leaves may dry off 

 before much ventilation is required. 



Watering. Plants that are growing slowly do not need 

 much water, while those that are growing vigorously need a 

 great deal of it. Growing plants need water whenever they 

 are dry. In bright, warm weather a rapidly growing crop 

 in hotbed or cold frame will need watering every day, while 

 in cloudy, moist weather perhaps no water will be needed for 

 a week. In fact, watering in cloudy weather seems to 

 encourage disease. When applying water see that the soil 

 is wet as far down as the roots extend. It is only the 

 beginner who just wets the surface soil and thinks the plants 



