WATERING, HEATING, VENTILATING AND SHADING 151 



percentage of coarse sand, require more water because of 

 loss by percolation and evaporation. 



The location of the beds and heating pipes should be 

 considered with reference to the water requirement of 

 the plants. If solid beds are used and the heating pipes 

 are remote, less water will be needed than when raised 

 benches are employed with the heating pipes under them. 



No rules can be given regarding the amount of water 

 which should be applied. Enough water should be used 

 to keep the soil moist, but over-watering should be care- 

 fully avoided, for this makes soft, tender tissues, and with 

 crops like tomatoes and cucumbers may cause excessive 

 stem and leaf growth with a poor setting of undersized 

 fruit. It is possible to apply so much water that the 

 plants become stunted and refuse to make satisfactory 

 growth. The dangers of over-watering in relation to 

 diseases have been indicated in previous chapters. 



Insufficient watering may be just as harmful as over- 

 watering. It necessarily results in small plants and poor crops. 



It is important to be thorough in watering. The water 

 should be uniformly applied over the entire bed surface. 

 Sometimes dry areas appear here and there, and it is 

 often an advantage to water these before time for the 

 next general watering. Enough water should be applied 

 each time to moisten the soil to the entire depth of the 

 beds. A few careful examinations of the beds, made 

 several hours after each application of water, will enable 

 the grower to determine whether a sufficient amount has 

 been used to moisten the beds to their full depths. 



When to water. The frequency of watering will de- 

 pend on several factors. As previously stated, transpira- 

 tion of water from the leaves and evaporation from the 

 soil are much more rapid when there is warm, sunny 

 weather, and at such times it is necessary to apply water 

 more frequently than during cool, dull, cloudy weather. 

 In the winter, when the days are short and there is little 



