CONSTRUCTION OF GREENHOUSES 
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sash are hinged on the headers, opening at the ridge; 
while there is, on the other hand, greater danger of cold 
drafts striking the plants, and rain and snow are easily 
admitted with this form of ventilation. But when houses 
are used until midsummer or later, hinging on the header 
is probably the better plan. Side ventilators are often 
provided, but many growers regard them as of doubtful 
utility. They are most useful in warm weather. But 
whatever the method of ventilation, it is of the greatest 
importance that the ventilating machinery work easily. 
183. Beds, benches and walks. — A few years ago green- 
house growers thought it essential to provide benches 
with bottom heat for practically all greenhouse crops, 
but the opinions held today are different. In many 
of the largest and most successful houses there are no 
benches or even beds with board, brick or concrete sides. 
These mammoth houses often have large doors at the 
ends so a horse and cart can enter with manure or other 
supplies. It is also possible to use plow and harrow in 
the preparation of the soil for planting. While all green- 
house growers do not approve of horse tillage under 
glass, some of the most successful growers always use 
horse implements in preparing ground for the fall crop. 
Benches are convenient in the handling of flats and 
potted plants, but they are expensive to construct and 
maintain unless made of concrete. 
Solid beds, with or without sides, provide more uni- 
form soil conditions than do shallow beds. There is less 
danger of injury from improper watering and, therefore, 
the chances of success are increased. Solid beds are espe- 
cially advantageous when the watering must be intrusted 
to men of limited experience. 
The walks should be arranged so that all the beds can 
be cared for conveniently. Beds or benches 5 feet wide 
and walks or alleys 18 inches in width make a desirable 
combination, although the relative width of beds in com- 
