396 VEGETABLE FORCING 
may be necessary. Asa rule, the opening is made on the 
side away from the wind, so that the wind will not blow 
into the frame. If only a small amount of ventilation is 
needed, every other of perhaps every third or fourth sash, 
moved only an inch or two, will admit sufficient air. 
When there are no cross bars, blocks of wood may be 
placed under the ends of the sash or at some distance 
from the ends of them, as shown in Fig. 1388. This system 
is somewhat objectionable on account of its tendency to 
warp the sash. In warm, sunny weather the sash may 
be entirely removed during the day and replaced on the 
frames in the evening. A careful study of the appearance 
of the plants will enable the gardener to determine 
whether they are being properly ventilated. 
Cloth covers are removed from the frames whenever 
the weather will permit. While they conserve heat they 
also exclude sunlight, and if they are kept on too much 
of the time the plants will become weak and spindling 
and subject to disease. 
Control of pests.—For methods of controlling various 
insect and fungous enemies, see Chapters VII and VIII, 
and notes on different classes of vegetables. 
VEGETABLES GROWN IN FRAMES 
Asparagus may be forced at any time during the winter 
in heated frames. The roots from which the shoots are 
to be grown are dug late in the fall and stored in a cool, 
moist place until wanted for use. The details of culture 
are essentially the same as when the crop is forced in the 
greenhouse. See Chapter XII for particulars. 
Bean.—This vegetable is sometimes grown in frames 
as a spring crop. The covering of cloth or glass should 
be used for about a month, or longer in the coldest sec- 
tions, and then no further protection need be given. An 
excellent plan is to plant bush beans at proper intervals, 
in rows not less than 22 inches apart, between rows of 
