Hotbeds and Cold-frames
Plants can be advantageously started and even grown on to the size for
setting in open ground in hotbeds. In building these of manure it is
important to select a spot where there is no danger of standing water,
even after the heaviest rains, and it is well to remove the soil to a
depth of 6 inches or 1 foot from a space about 2 feet larger each way
than the bed and to build the manure up squarely to a hight of 2 to 3
feet. It is also very important that the bed of manure be of uniform
composition as regards mixture of straw and also as to age, density and
moisture, so as to secure uniformity in heating. This can be
accomplished by shaking out and evenly spreading each forkful and
repeatedly and evenly tramping down as the bed is built up. Unless this
work is well and carefully done the bed will heat and settle unevenly,
making it impossible to secure uniformity of growth in different parts.
Hotbed frames should be of a size to carry four to six 3×6-foot sash,
and made of lumber so fastened together that they can be easily knocked
apart and stored when not in use. They should be about 10 inches high in
front and 16 or 18 inches at the back, care being taken that if the back
is made of two boards one of them be narrow and at the bottom so that
the crack between them can be covered by banking up with manure or
earth. In placing them on the manure short pieces of board should be
laid under the corners to prevent their settling in the manure unevenly.
I prefer to sow the seed in flats or shallow boxes filled with rich but
sandy and very friable soil, and set these on a layer of sifted coal
ashes covering the manure and made perfectly level, but many growers sow
on soil resting directly on the manure; if this is done the soil should
be light and friable and made perfectly level. A perspective view of a
three-sash hotbed is given in Fig. 13, and of a cross-section in Fig.
14.
[Illustration: FIG. 13--THREE-SASH HOTBED]
In some sections, particularly in the South, it is not always easy to
procure suitable manure for making hotbeds, so these are built to be
warmed by flues under ground, but I think it much better where a fire is
to be used that the sash be built into the form of a house. A hotbed of
manure is preferred to a house by some because of its supplying uniform
and moist bottom heat--and one can easily give abundant air; but the
sash can be built into the form of a house at but little more expense,
and it has the great advantage of enabling one to work among the plants
in any weather, while, if properly built, any desired degree of heat and
ventilation can be easily secured. Except when very early ripening fruit
is the desideratum, plants started with heat but pricked out and grown
in cold-frames without it, but where they can be protected during cold
nights and storms, will give better results than those grown to full
size for the field in artificial heat.
[Illustration: FIG. 14--CROSS-SECTION OF HOTBED]
[Illustration: FIG. 15--COLD-FRAMES ON HILL-SIDE]
=Cold-frames.=--In locations where tomatoes are much grown large areas
are devoted to cold-frames covered either by sash or cloth curtains.
Sash give much better protection from cold and on this account are more
desirable, particularly where very early fruiting is wanted, but their
first cost is much greater and the labor of attending to beds covered by
them is much more than where cloth is used. Sash-covered beds should be
of single width and run east and west, but if the beds are covered with
cloth it is better that they be double width (12 feet) and run north and
south. The front of the single and the sides of the double width beds
should be 8 to 10 inches high, held firmly erect by stakes and perfectly
parallel, both horizontally and vertically, with the back or with the
central support. This should be 6 inches higher than the front. The
cross strips, when sash are used, should be made of a 3-inch horizontal
and a 1-1/2-inch vertical strip of 1-inch lumber nailed together very
firmly in the form of an inverted T, the vertical pieces projecting 1
inch at each end and resting on the front and back of the bed and
forming supports and guides for the sash. Some growers use vertical
strips as heavy as 2×3 or 4 inches for stepping across the beds. When
the plants are to be taken to the field, the sash and guides can be
easily removed. (Fig. 15.)
Ground to be covered with cold-frames should be made very friable and
rich by repeated plowing and working in of a liberal dressing of
well-rotted stable manure and wood ashes. In southwestern New Jersey,
where immense areas of early tomatoes are grown, the soil of the beds
for a depth of about 6 inches is removed and a layer 3 to 5 inches deep
of well-rotted stable manure is placed in. That made of a mixture of
manure from horses, cattle and hogs is preferred. It is important that
the manure be so well rotted that it will not heat, and so dry that it
will not become pasty when tramped into a firm, level layer. On this
they place a layer of nearly 3 inches deep of rich, friable, moderately
compact soil and prick out the plants into this. The roots soon bind the
manure and soil together and by cutting through the manure so as to form
blocks one can carry the plants to the fields with but very little
disturbance of the root.
=Cloth covers for beds= should be made of heavy, unbleached sheeting or
light duck, and it is better that the selvage run up and down the bed
rather than lengthwise. The cloth is torn into lengths of about 13 feet
and then sewn together with a narrow double-stitched flat seam so as to
form a sheet 13 feet wide and about 8 inches longer than the bed. The
edges are tacked every foot to the strips about 2 inches wide by 7/8
inch thick with beveled outside edges and laid perfectly in line. A
second line of strips is then nailed to the first so as to break joints
with it and so that the two will form a continuous roller about a foot
longer than the bed with the edge of the curtain firmly fastened in its
center. The center of the curtain is secured to the central ridge of the
bed by strips of lath. When rolled up, the rollers are held in place by
loops of rope around their ends and when they are down they are held by
similar loops to the notched tent-pins driven into the ground or to
wooden buttons fastened to the sides and ends of the frame as shown in
Fig. 16.
[Illustration: FIG. 16--TRANSPLANTING TOMATOES UNDER CLOTH-COVERED
FRAMES (Photo by Prof. W. G. Johnson)]
Cloth covers are sometimes dressed with oil, but this is not to be
recommended, though it is an advantage to have them wet occasionally
with a weak solution of copper sulphate or with sea water as a
preservative and to prevent mildew. Such covers, well cared for, may
last five years or be of little use after the first, depending upon the
care given them. They can be made from 50 to 200 feet long and two men
can roll them up or down very quickly.
When cloth covers are used the supporting cross-strips should not be
over 3 inches wide nor more than 3 feet apart; sometimes the strips are
made to bind the sideboard and ridge together by means of short pieces
of hoop iron or of barrel hoop. These are so placed and nailed as to
hold the upper edge of sideboards and of the central ridge flush with
the cross-strips, thus forming a smooth surface for cloth to rest on and
enabling one easily to "knock down" and remove the frames to facilitate
the taking of the plants from the bed to the field and the storing of
the frames for another season.
=Flats for starting seeds.=--Any shallow box may be used or the plants
sown directly in the beds without them, but flats of a uniform size are
to be preferred--these will pack well on the greenhouse shelves; or in
the hotbed we make them with 7/8 inch thick ends and 1/2 inch thick
sides and bottom, the latter if of a single board having four half-inch
holes for drainage and in any case having two narrow strips about 1/4
inch thick nailed across their bottoms so as to allow drainage water to
escape freely when the boxes are set on hard, cool floors. Two or three
such boxes, 35-1/2 inches long, 12 inches wide and 3 inches deep, will
be sufficient to start plants enough for an acre. I like to use similar
boxes only 4 inches deep for growing the plants after they are pricked
out, particularly if this is to be done in a greenhouse, as by turning
them we can equalize exposure to light and thus distribute the plants in
the field where they are to be set with the least possible disturbance.
One would need nearly 60 such boxes for plants enough for an acre. On
account of the lessened necessity for watering when plants are set in
beds rather than in boxes, many growers prefer to grow their plants in
that way.