286 VEGETABLE FORCING 
ture on cloudy days during the winter should be about 70 
degrees. In warm, bright, sunny weather, no injury will 
result from very high temperatures. It is a common 
occurrence for the temperature to rise in the houses to 
over 100 degrees during the months of June and July. 
Ventilation—As previously stated (page 166), the 
houses should be ventilated as freely as weather condi- 
tions will permit. Some fresh air should be admitted 
every day, even in the coldest weather. In warm 
weather it is desirable to keep the ventilators open all 
night. During the late spring and summer months doors 
and ventilators should be opened full width unless 
storms make it necessary to close them for a short time. 
Thorough ventilation is exceedingly important in the 
control of fungous diseases. It is also an aid in the 
pollination of the flowers. 
Cultivation.—When the beds are not mulched it is im- 
portant to cultivate the soil as often as may be necessary 
to keep the surface in a loose, friable condition. When 
21% feet or more of space is allowed between rows, it is 
possible to till the soil with a wheel hoe. Tillage must 
not be deep enough to injure the roots of the plants. 
Mulching.—The majority of greenhouse growers of 
tomatoes mulch the beds with horse manure. Among the 
advantages which may be mentioned are the conserva- 
tion of soil moisture, prevention of weed growth, saving 
of labor in cultivating, saving of labor in watering so 
frequently, and the feeding of the plants by food leached 
from the manure after every surface application of water. 
Unless the soil is excessively rich in nitrogen, mulching 
with manure is probably always beneficial, and should 
there be a surplus of this element in the soil, cut straw 
might be substituted. 
Mulching is most beneficial when surface watering is 
practiced, but it is also an advantage with sub-irrigation. 
Almost any kind of organic material may be used for 
