HOTBEDS AND GREENHOUSES
Whether to get an early start on the garden or for raising plants
for field crops, a hotbed is all but indispensable. In making a
hotbed what we seek to do is to imitate Nature at her best, so get
the best soil and the sunniest spot you can find.
In all hotbeds the underlying principle is the same: They are
right-angled boxes covered with glass panes set in movable frames
and placed over heated excavations. The bed may be of any size or
shape, but the standard one is six feet wide, since the stock glass
frames are usually six feet long by three feet wide. You can have
any length needed to supply your requirements. "Tomato Culture," by
A. J. Root, tells us that the cheapest plan is to get some old
planks, broken brickbats or stone, and piece together a box-like
affair in proper shape: to provide drainage, the front should be at
least ten inches above the ground and the rear fourteen inches. A
hotbed knocked together in this way is all right to start with, if
you cannot do any better, but will last only two or three seasons.
For a permanent bed, probably the best way is to make cement walls
extending to the bottom of the manure. The bed ought to face south
or southeast and be well protected on the north. It should be banked
all around with earth or straw to keep out the cold, and mats or
shutters should be provided for extra cold weather. The best
material for heating the bed and the most easily obtained, is fresh
horse manure in which there is a quantity of straw or litter. This
will give out a slow, moist heat and will not burn out before the
crops or the plants mature. Get all the manure you need at one time.
Pile it in a dry place and let it ferment; every few days work the
pile over thoroughly with a dung fork; sometimes two turnings of the
manure are enough, but it is better to let it stand and heat three
or four times.
"You can make a hotbed also on top of the ground without any
excavation. Spread a layer of manure evenly one foot in depth and
large enough to extend around the frame three feet each way. Pack
this down well, especially around the edge, put on a second and
third layer until you have a well-trodden and compact bed of manure
at least two and one half feet in depth. Place the frame in the
center of this bed and press it down well." A two-inch layer of
decayed leaves, cut straw, or corn fodder, spread over the manure in
the frame and well packed down, will help to retain the heat.
Ventilate the bed every day to allow steam and ammonia fumes to pass
off.
"The soil inside should be equal parts of garden loam and
well-rotted barnyard manure. Tramp well the first layer of three
inches. To make it entirely safe for the plant seeds in the hotbed,
add another layer of the same depth. Use no water with garden loam
and manure if you can possibly help it."
"Before sowing any seeds put a thermometer in the bed three inches
deep in the soil. If it runs over 80 degrees Fahrenheit, do not sow.
If below 55 degrees it is too cold; you will have to fork it over
and add more manure. If the bed gets too hot, you can ventilate it
with a sharp stick by thrusting it down into the soil."
Another way that the old gardeners have to make a hot bed is with
fire. On a large scale this is cheaper, though more complicated than
the fermentation of manure. In making this kind choose your location
and build the frames as before. "Cut a trench with a slight taper
from the east end of the plot to the end of the hotbed, and on under
the ground to about four feet beyond the end of the bed. This taper
to the outlet will create a draught and so keep a better fire. Arch
this over with vitrified tile. The furnace end where the fire is
should be about six feet away from the bed. When the trenches are
completed, cover over with the dirt that was taken out of them. Two
such trenches under the frames will make a good hotbed. Anyone can
do this sort of work."
A hotbed can also be heated by running steam pipes through the
ground, but unless you happen to be where exhaust steam could be
used, this method is not economical except for big houses. The care
and expense of a separate steam plant would be too great to pay,
unless for growing winter vegetables for market or flower culture.
If you go into that on a scale large enough to pay, new problems at
once demand solution.
Vegetables under glass have kept pace with other crops. Within
fifteen miles of Boston are millions of square feet of glass devoted
to vegetables, chiefly lettuce. There are more than five million
feet in the United States used for other crops. Ordinarily, under
favorable conditions, glass devoted to this work will yield an
average of fifty cents per year per square foot.
About the lowest estimate of cost per sash is five dollars; this
amount includes the cost of one fourth of the frame and covers.
There are usually four sashes to one frame. A well-made mortised
plank frame costs four to six dollars. A sash, unglazed, costs from
one to two dollars. Glazing costs seventy-five cents. Mats and
shutters cost from fifty cents to two dollars per sash, depending
upon the material used. Double thick glass pays better in the end as
being less liable to breakage. These prices vary greatly, however.
The following sample estimate by a gardener is for a market garden
of one acre, in which it is desired to grow a general line of
vegetables. It supposes that half of the acre is to be set with
plants from hotbeds.
One eighth acre to early cauliflower and cabbage, about 2000 plants,
if transplanted, would require two 6 X 12 frames, from two hundred
to two hundred and fifty plants being grown under each sash.
These frames may be used again for tomato plants for the same area,
using about 450 plants. This will allow a sash for every 55 plants.
One frame should be in use at the same time for eggplants and
peppers, two sashes of each, growing fifty transplanted plants under
each sash.
Two frames will be required for cucumbers, melons, and early
squashes; for extra early lettuce, an estimate of sixty to seventy
heads should be made to a sash. It is assumed that celery and late
cabbages are to be started in seed beds in the open.
In the fashionable suburbs of Boston "one hotbed 3 X 6 feet was used
in which to start the seeds of early vegetables. Plantings were made
in the open ground as soon as the weather permitted, and were
continued at intervals throughout the season whenever there was a
vacant spot in the garden. The following varieties of vegetables,
mostly five-and ten-cent packets, were planted: Pole and wax beans,
beets, kale, cabbage, carrots, cauliflower, celery, corn, cucumbers,
corn salad, endive, eggplant, kohlrabi, lettuce, muskmelon, onions,
peppers, peas, salsify, radish, spinach, squash, tomatoes, turnips,
rutabagas, escarole, chives, shallot, parsley, sweet and Irish
potatoes, and nearly a dozen different kinds of sweet herbs."
"In the larger garden, tomatoes followed peas, turnips the wax
beans, early lettuce for fall use took the place of Refugee beans.
Corn salad succeeded lettuce."
"The spinach was followed by cabbage, while turnips, beets, carrots,
celery, and spinach gave a second crop in the plot occupied by
Gardus peas and Emperor William beans."
"Winter radishes came after telephone peas, Paris Golden celery was
planted in between the hills of Stowell's blanching. The plot of
early corn was sown to turnips. The hotbed was used during the late
fall and winter to store some of the hardy vegetables, and the
latter part of October there was placed in it some endive, escarole,
celeriac, and the remaining space was filled up by transplanting
leeks, chives, and parsley." (Bailey, "Principles of Vegetable
Gardening," page 38.)
"If spinach is grown in frames, the sash used for one of the late
crops above may be used through the following winter.
"This, like the last case, makes a total of five frames, the cost,
depending on make and material, from one to five dollars; twenty
sash and covers, at, say, $2.75, $55; manure at market price,
calculating at least three or four loads per frame. This is a
liberal estimate of space, and should allow for all ordinary loss of
plants, and for discarding the weak and inferior ones. It supposes
that most or all of the plants are to be transplanted once or more
in the frames. Many gardeners have less equipment of glass." (Same,
pages 49-50 )
Growing vegetables under glass gives smaller returns than flowers;
as, for instance, a head of lettuce brings much less than a plant of
carnations, and suffers more from the competition of southern crops.
Nevertheless, the greenhouse-grown vegetables have come into
prominence lately because they can be raised in houses that are not
good enough for flowers. Lettuce and tomatoes are the principal
crops; some growers raise thousands of dollars' worth each year. The
greenhouse is also used for forcing plants which are afterwards
transplanted to the open air. This develops them at a time when they
could not grow outdoors and gives them such a start that they are
very early on the market, thereby realizing the highest prices.
"Nearness to market is the most important feature in a greenhouse.
In large cities, manure, which is the chief fertilizer, can be had
in most cases for the hauling. The short haul is an important item,
and, most important of all, the gardener who is near the market can
take advantage of high prices, if the grower is near enough to the
city to make two or three trips; in such a fluctuating market as New
York, it is to his advantage."
Some kind of a greenhouse is necessary, but one large enough to
produce a living would cost a very large sum. Vegetable raising
under glass has been made profitable in special localities where
nearly the whole community gives its time to building up the
industry, but complete success can be attained only by having
absolute control of all the conditions entering into production, and
giving assiduous and undivided attention to detail.
Leonard Barron, in the _Garden Magazine,_ says: "The best type of
greenhouse for all-round purposes is unquestionably what is known as
the even span--that is, a house in which the roof is in the form of
an inverted V, so as to be exposed as much as possible to sunlight,
and having the ridge-pole in the center. All other types of houses
are modifications from the simplest form, and are designed in some
way or other to fit some special requirements. These requirements
may be: the cultural necessities for some particular crop; a desire
to have the atmospheric conditions inside more or less abnormal at
given seasons (as in a forcing house); or an adaptation to some
peculiarity of the situation, as when a greenhouse is built as an
adjunct to other buildings."
"It is plain common sense that the ideal greenhouse is one in which
the light is most nearly that which exists outside, and in which the
heat is as evenly distributed. It is practical experience that a
structure with as few angles and turns m it as possible and with a
minimum of woodwork in its superstructure, best answers these
conditions.... Greenhouse building has developed into a special
industry, and the modern American greenhouse is the highest type of
construction. It is built with as careful calculation to its
situation and its requirements as is the country dwellinghouse. Such
a thing naturally is not cheap."
"The low-priced 'cheap greenhouse' is a makeshift of some sort.
Perhaps its roof is constructed of hotbed sash, a perfectly feasible
method of construction, which for ordinary, commonplace gardening
will answer admirably. Or, its foundation is merely the plain earth.
Such a building does admirably in the summer time, and even in the
late spring and early autumn; but woe betide the enthusiastic
amateur in winter, who, being possessed of one of these light
greenhouse structures, has indulged in a few costly, exotic plants.
They will be frozen, to a certainty! It is economy to pay a fair
price in the beginning to secure a properly built greenhouse that
will withstand the trials of winter."
"If iron frame is used instead of wood there is greater durability,
and the structure being more slender, will admit more light, but the
cost will be increased."
"It makes very little difference in cost what shape of house is to
be erected. The cost per lineal foot for an even span is practically
the same as for a lean-to of the same length and width. In the
lean-to, in order to get the sufficient bench and walk space inside,
it is necessary to carry the roof to a point much higher than in the
even span. The extra framework and material for the roof cost a good
deal, yet add practically nothing to the efficiency of the house."
"Heating of greenhouses is best done by hot water, and in a small
house the pipes may well be connected with the heating system used
for the dwelling, if the greenhouse and the home are within any sort
of reasonable distance from each other. For large houses, or ranges
of several houses together, the independent heating plant is
necessary. Steam is used for heating by commercial florists, but it
is economical only on a large scale."
"As a uniform temperature must be maintained in the house, the
fires, where steam is used, need watching continuously during cold
weather, for the moment the water ceases to boil, the pipes cool off
and a considerable time is consumed in starting the heat running
again. With hot water there is much more latitude in attention, for
though the fires dwindle' the water which fills the pipes will carry
heat for a long time, and it will circulate until the last degree is
radiated. But a hot-water system costs in the installation about one
fourth more than steam. Very small houses may be successfully heated
by kerosene stoves, which may be placed inside the house. A much
better way would be to use oil heaters for an inside water
circulation, carrying off all products of combustion by means of a
flue. Coal stoves should never be installed inside the house. It has
been done successfully by some amateurs, but the danger of coal gas
being driven back into the house by a down draft in the chimney is
too great a risk. Coal gas and illuminating gas are two virulent
poisons to plants."
It is obvious that the amateur must proceed with great caution in
undertaking intensive cultivation under glass. Build at first the
simplest and least expensive kind of hotbeds or greenhouses. It
takes three to five seasons to train even an experienced farmer
along these special lines. Separate crops require special treatment.
Do not experiment, but follow well-tried procedure. It is
comparatively easy to farm an acre under glass, but it should be
worked up to, each step being taken only after a solid foundation is
ready to build on. Learn by your mistakes. Don't get discouraged by
failure. By not making the same mistake twice, you will soon learn
by experience just what is essential to production. The more you
learn about the way nature does things, the more likely you will be
to succeed when you seek to imitate her.