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 
