16 DREER’S VEGETABLES UNDER GLASS. 
usually find a suitably sheltered place for them on the south- 
ern side of buildings or shrubbery, but the extensive operator 
always builds a board fence to shield his glass from the north 
and west winds. See the remarks on this subject elsewhere, 
in connection with the cold frame culture of lettuce. To 
shut off the cold winds is an important matter. Do not 
neglect it. 
CHANGE OF SOIL. It is a matter of common observa- 
tion that new structures (frames and greenhouses) are usu- 
ally free from disease. This means that disease germs are 
not likely to be present in new and clean places. Hence, it 
is strongly advised that the soil of the cold frame, for a 
depth of several inches, be changed every year. We believe 
the labor and expense are warranted, whether there is dis- 
ease in the soil or not. There are expert operators, to be 
sure, who do not change the soil and who succeed. But mil- 
dew and other diseases are far more prevalent where the 
same soil is used year after year. Summer cultivation of the 
frames, in vogue among large operators, is the next best 
thing to changing the soil. 
CARE OF FRAMES IN WINTER. Instead of laying 
down fixed rules for the management of cold frames in win- 
ter it is deemed best to refer the reader to the chapter on 
lettuce culture, which treats the subject in a definite manner. 
The principal thing to bear in mind is that ventilation must 
be given every day during winter when the sun shines, and 
even in cloudy weather when the ground under the glass is 
unfrozen or likely to thaw. Over ventilation seldom does 
harm to hardy plants, while under ventilation is almost cer- 
tain to be followed by weakness and disease. 
A shutter made of light boards, called a ‘‘lid’’ by Phil- 
adelphia market gardeners, may be used at night upon 
sashes in winter if desired, but the shutter is more commonly 
employed in connection with hot bed work. For a design 
