Intensive gardening under sash or cloth covers has become one of the
most popular and, in certain localities where the conditions are
suitable, one of the most profitable lines of outdoor work. The trucker
and the market gardener of the present day have been compelled by
keen competition and a constantly increasing demand for high-grade
products out of season to provide special facilities for increasing and
improving the product, as well as to take advantage of every favorable
natural condition. Many localities are especially favored with an
abundance of sunshine at all seasons of the year, and at the same
time their climate, due to the influence of large streams or near-by
bodies of water, is mild and free from extremes of temperature. In such
localities it would be possible to grow lettuce, radishes, and similar
crops during the entire winter without protection were it not for a few
cold days and nights. A very slight covering or the application of a
small amount of heat will, as a rule, carry the plants through in good
condition. This industry may readily be combined with regular truck
farming, as it furnishes remunerative employment during the winter
months. A comparatively small area is necessary for the frames, but
several times that acreage of land should be available, so that the
site of the frames may be changed every few years to safeguard against
diseases and insect injuries.
_Cloth-Covered Frames._--The type of frame or bed varies with the
different localities and is ordinarily no more elaborate or expensive
than is necessary to protect the crops. In North Carolina and South
Carolina the type of frame generally used is that having for the sides
two lines of 12-inch boards set on edge and held in place by means
of stakes driven into the ground. The covering of cheap unbleached
muslin is supported on strips of wood 1 inch thick and 2-1/2 or 3
inches wide, which are raised in the center by being carried over the
top of a stake; the ends are held down by nailing to the sides of the
bed. Most of these frames are temporary and are taken apart and stored
during the summer months. Before placing the frames in position in
the autumn the soil is plowed, thoroughly fitted, and given a liberal
dressing of well-rotted stable manure and commercial fertilizers.
The placing of the boards will cause some trampling of the bed, and
before putting in the ends and nailing on the rafters or strips to
support the cloth it is desirable to loosen the soil again by means of
a harrow or cultivator. The stakes for supporting the cross strips or
rafters are then driven through the center and the strips nailed in
place at intervals of 4 feet. The ends are inclosed by means of 12-inch
boards, and the bed is then ready for the cloth cover. The cloth is
first stitched, with the strips running lengthwise of the bed, into
one great sheet large enough to cover the entire bed. This sheet is
fastened on the north side of the frame by nailing over it plastering
laths or similar strips of wood. The cloth should not be fastened to
the top edge of the board but on the side, 1 or 2 inches below the top.
For fastening the sheet on the south side of the frame short loops of
string or cloth are attached to its edge and these are looped over
nails driven into the side of the bed.
_Sash-Covered Frames._--In the tidewater region of Virginia the frames
are covered with hotbed sash. The climate of Norfolk is a little too
severe for the use of cloth except for early autumn and spring crops.
A number of growers in the vicinity of Norfolk handle sash-covered
frames occupying as much as 3, 4, or 5 acres each season. For the sides
and ends of these frames the same class of cheap lumber as for the
cloth-covered frames is used.
_Heated Frames._--Farther north, near Chicago, St. Louis, Cleveland,
Detroit, Baltimore, Philadelphia, Cincinnati, New York, and Boston,
sash-covered frames are extensively used for growing early vegetables.
This work is practically the same as that found at Norfolk, except
that the frames are constructed over an excavation which is filled
with fermenting manure to provide heat. Where manure-heated beds are
extensively used for growing early vegetables a long, shallow pit is
opened, the manure is trodden in, and 12-inch boards are fastened to
stakes to form the sides. The board on the north side is raised a
little higher than the one on the south side in order to form a slope
for the glass. A few strips are nailed across the bed to prevent the
sides from coming in by the pressure of the manure or soil that is
banked on the outside, and the sash simply rest on the sides without
any guide or supporting strips between them. Straw mats and board
shutters are employed as a protection for the sash during cold weather.
_Temperature of Frames._--The temperature at which the air of the
beds should be carried will depend entirely upon the crop being grown.
Thermometers should be placed at intervals in the beds, as it is not
safe to judge the temperature by personal sensation. If lettuce,
parsley, or radishes are growing in the beds, the temperature should
not go above 70° F. before ventilation is given; on the other hand,
if the frames are filled with cucumbers, eggplant, or peppers, the
temperature may run 8 or 10 degrees higher. It should be borne in mind
that any covering, whether cloth or sash, will exclude a part of the
light, and every precaution is necessary to prevent the plants becoming
"drawn." The safest plan is to keep the temperature a trifle low and
thus retain the plants in a strong, thrifty condition. Where tender
plants are being grown under cloth there is greater danger of injury
from keeping them covered too tightly than from exposure to moderate
cold.
[Illustration: SHOWING VEGETABLES GROWING IN HOTBED]