elevated in temperature, renders it also comparatively dry; the sun drinks
up the moisture which is deposited near the surface, or which may rise to
that position; and by an exceedingly powerful influence effectually
prevents the accumulation of moisture about the exposed parts of the
plants. The atmosphere is nevertheless not in an arid state; the
evaporation from a well-moistened soil effectually prevents this from
being the case, but the excessive heat also as effectually and continually
prevents an undue accumulation of moisture in the atmosphere. The
application of this fact, to artificial practice, is plain; a less amount
of moisture artificially applied, in comparison with the temperature, must
be permitted, than when the cultivation of those plants is attempted whose
natural habitats are less strongly featured in this respect.
Such considerations as these naturally force on us the conclusion, that it
is vain to attempt the cultivation of this noble fruit, except during that
portion of the year when the sun exerts his greatest power in our
latitude. It is not because they cannot be induced to grow at any other
period of the year, for the mere extension of vegetable tissue will go on,
though the influence of the natural agents is but limited and feeble; but
it is because maturity, perfect development, and, above all, the full
assimilation of the sap, cannot take place sufficiently to ensure a good
flavour in the fruit, except light and heat are not only unimpeded and
constant, but powerful and united in their action.
CHAP. X.
CONCLUDING REMARKS.
I will here briefly recall attention to a most important point which the
cultivator should continually keep in view: it is most important that he
should _study Nature_; for if we may believe our senses, or place any
confidence in overwhelming evidence, we may be certain that all the
conditions we observe in a natural state of things, have been planned by
an All-wise hand; and further, that a finite mind can never attempt with
success, either to surpass or to dispense with any portion of that which
an infinite being has ordained. "Order is Heaven's first law," and in
whatever we may attempt to do, we shall not be wise, if we endeavour to
effect our purpose by any means which may distort the fair proportions
which unaided nature presents to our view. In cultivating plants,
therefore, we should administer the conditions which are favourable to
their growth and development, in somewhat the same proportions each to the
other, in which they are naturally blended--not supplying one essential,
in an undue manner, and, at the same time, neglecting others; for
successful cultivation must ever depend upon the connection and influence
of numerous circumstances upon each other, and can never be attained,
unless these conditions are complied with, either designedly, or, as it
often happens, by mere accident.
Another point which it is important to keep in view, is that instructions
should be studied, rather than copied, in their application to practice.
No instructions can be given that should be blindly and implicitly
followed. The circumstances under which plants are placed are varying
every day, and even every hour, and, to be successful, horticultural
practice must be varied also. It must, however, be varied according to
principle. But even what are regarded as established laws and principles
should not be heedlessly followed; to be truly successful, a man must not
only be a practical enthusiast and a keen theorist; he must also be a
skilful experimentalist: his experiments and their results, if carefully
watched, deduced, recorded, and studied, will serve to guide him for the
future.
APPENDIX.
_On Heating, Ventilating or Aerating, and Covering._
Since the publication of the first edition of this work in 1844, the views
expressed in the second chapter, with reference to structures best adapted
for Cucumber culture in the winter season, have met with much
corroborative support. Respecting the questions of heating, ventilation,
and covering, a few more words may be added.
I have before recommended hot water tanks for supplying bottom heat, with
attached pipes for the circulation of hot water to warm the atmosphere. I
can see no reason for recommending any other arrangement now; for the
experience of successive years goes to show that hot water, applied on
sound principles, is, above all other means of heating, effective in its
operation; and as to the question of expense, raised as an objection to it
by some, it is sufficient to say, that, although one hot water apparatus
may be fitted up in an expensive manner, another may be rendered perfectly
successful in its operation, at the same time that it is extremely simple
in its arrangements, and correspondingly inexpensive in its cost.
A seeming error in the engraving, at p. 18, has been pointed out to me. In
the description of the sketch it is stated that, "a series of pipes
attached to the same boiler [which heats the tank] would supply the
requisite heat to the atmosphere." The sketch itself shows these pipes to
be considerably above the level of the water in the tank, and where they
could not, consistently with the other arrangements, be thus employed.
This may be explained thus:--the sketch was introduced rather for the
purpose of illustrating certain proposed arrangements, as regards bottom
heat and ventilation, than as furnishing an exact and detailed design for
a model structure; and thus it happened that the pipes were merely shown
to be placed at the front part of the house, to indicate that this was
their proper relative position. There would be no practical difficulty in
placing the pipes lower down, and nearly close to the front wall, so as to
admit of the proposed connection; all that would be required to effect
this, being to fix the slab, on which they rest--and which prevents the
air from rushing upwards into the atmosphere of the house at this
point--in a sloping position, instead of a horizontal one.
The principle involved in the plan proposed for aeration or ventilation,
is no doubt a sound one; and though the plan which is more particularly
described may be modified and varied, yet it is believed to be efficient
for its intended purpose.
There can be no doubt that the admission of cold air to a structure in
which tender plants are being forced, either during winter or early
spring, is materially hurtful to the plants, in proportion to the
tenderness of their constitution; and the Cucumber being, under those
circumstances, a plant of a very tender and delicate nature, is especially
susceptible of harm from this source. As a consequence resulting from this
fact, there can be little hesitation in affirming that whatever fresh or
external air it may be necessary to admit, during the period referred to,
should be warmed before it reaches the plants, and in being warmed not
burned, but supplied with the additional moisture its increased heat
capacitates it to take up, and which, to be congenial to vegetation, it
requires. This is provided for by the plan already recommended, where the
cold air is made to pass through the tank containing the heated water
which warms the soil. By a perfectly practicable modification of this
arrangement, not only may this result be secured, but also the continual
circulation of the internal atmosphere may at pleasure be assisted and
accelerated, during the time when it might not be necessary to admit fresh
air. This would be an additional advantage. The arrangement proposed to
effect this, is to conduct the cold external air through a heated chamber
containing the tanks--these latter being covered, but also admitting of
being opened to any extent to supply moisture or steam in the proportion
required. The cold air, after passing upwards through the chamber, escapes
at the front of the house, and ascends to the upper part of the house,
from whence it finds its way downwards near the back wall, and there again
enters the chamber, through openings provided for the purpose. The
circulation of the internal atmosphere would be thus facilitated and
accelerated, even without the admission of any current of external air,
for, of course, there is more or less of this kind of movement going on in
the atmosphere, wherever and in whatever form a source of artificial heat
is present. Another mode of combining internal atmospheric motion, with
ventilation, and by which the cold air is warmed before it reaches the
plants, has been practised with very marked success, in a vinery at
Park-hill, Streatham, Surrey; and I have described it in the _Journal of
the Horticultural Society_[1] as follows:--"This plan consists in passing
a zinc pipe, thickly perforated with small holes, from end to end of the
vinery, and exactly beneath the range of hot water pipes, which heat the
structure. In the outer [end] wall, communicating with this perforated
pipe by means of a kind of broad funnel, a register valve is fixed, by
which the admission of air can be regulated with the utmost nicety, or the
supply be shut off altogether: this valve is fixed a little below the
level of the perforated pipe. The action of this contrivance was evident
enough from the motion communicated to the foliage of the vines; and its
effects were apparent in the unusually healthy and vigorous appearance
they bore, until their period of ripening. In this case, sufficient
moisture was kept up by syringing the walls and pipes, wetting the
pathway, and by the use of evaporating troughs, placed on the metal pipes,
and kept constantly filled with water."
In another communication published in the work already quoted,[2] after
alluding to the now well-known garden truism, that a comparatively low
night temperature is indispensable to the maintenance of vigorous growth
in plants of all kinds, I have advocated a more extended adoption of the
practice of night covering hot houses, as a means of permitting the low
night temperature required, and at the same time securing the plants
against the extreme cold to which they would thus be sometimes liable.
From the changeable nature of our climate, there is some difficulty in
apportioning the degree of applied heat, so as to suit exactly the
requirements of the plants in these respects; and it is especially
difficult to maintain with certainty the low degree of night temperature
which would be desirable, and at the same time avoid risking the safety of
the plants, through a sudden declension of the temperature of the exterior
air. At present this difficulty has to be met by extraordinary care on the
part of the gardener, and often by serious encroachments on his proper
time for study and for rest: even then sometimes without success. This end
would be much more effectually and certainly secured by a _complete
system_ of covering hot-houses and forcing-houses; and this plan would
secure the further advantage of avoiding the undue stimulation of the
plants by a then unnecessary amount of heat, applied solely to prevent the
very evil which covering also prevents, namely, the risk of excessive cold
during the night.
The principle upon which a covering acts most efficiently, is that of
enclosing a complete body or stratum of air exterior to the glass, this
body of air being entirely shut away from the surrounding outer
atmosphere. Air being a bad conductor of heat, the warmth of the interior
is by this means prevented from passing to the exterior atmosphere; or, in
other words, the exterior atmosphere, being prevented from coming in
contact with the glass, cannot absorb from the interior any material
proportion of its heat. To secure this advantage, however, the coverings
_must_ be kept from contact with the glass, and they should extend on
every side where the structure is formed of materials which readily
conduct heat--such as glass or iron. The coverings should in fact form
neither more nor less than _a close outer case_.
One point connected with the application of these coverings, which I
consider would constitute an improvement, and which, as far as I am aware,
has never been acted on, is that of having them to fit so accurately as to
exclude the external air (a matter of no difficulty in the degree
required), and then to have a series of ventilators provided, to stand
open during the night, whereby an interchange of the atmospheric volume
would take place throughout the night, without exposing the plants to
contact with cold air. The stagnation of the internal atmosphere would
thus be prevented, in consequence of the interior air and the air between
the glass and the covering being of different degrees of density, owing to
their being differently charged with heat. By this plan, therefore, I
conceive that direct benefit would accrue to the plants; and it would also
materially assist in preserving that cooler--but not cold--night
temperature, which the fear of injury from frost prevents from being more
fully realised in ordinary cases.
[Illustration]
The annexed diagram represents one of the many ways in which this idea
might be carried into practice. It will be understood that, as here shown,
the side shutters and end shutters (the latter not indicated), fit into
grooves, the upper groove being attached to iron pins, and thus fixed at a
proper distance from the building, without obstructing the passage of air
along the enclosed space; and that on the lower side being so fixed as to
exclude the external air in that direction. The top or roof shutters also
run into a groove along the ridge of the roof, and at the lower end fix
close down to the top of the side shutters, fastening with a button. Each
of the shutters should have a projecting fillet fixed on one side, so as
to shut close over the adjoining one. The shutters themselves should of
course be made of light frame-work, strengthened where necessary, with
small iron rods. The material used for covering them may be the asphalte
felt, now manufactured extensively for roofing purposes, or strong brown
paper, coated with tar; the latter is used extensively in Germany for this
purpose, and is found to be very durable and cheap; it is there even
preferred to every other material.
Though the covering of hot-houses has been already practised in some
cases, I am not aware of any one having adopted a close covering with the
view to facilitate ventilation or aeration during the night. It appears to
me that the circulation of air, secured by the means here proposed, would
have much influence in excluding cold, whilst at the same time it would
prevent the interior from becoming too warm and close.
_On Transplanting and the use of Turf Pots._
I have, at p. 26, given what appear to me to be some of the principal
reasons against the practice of transplanting, or planting out, Cucumber
and other plants. When this is done after any quantity of roots are
produced, some injury or check must be sustained during the process; and
checks of this kind are opposed to the realisation of the greatest results
within the shortest period, which of course is the great object in view.
Where it is inconvenient to plant the seeds in the places the plants are
intended to occupy, or to put out the young plants during the earliest
period of their development, or where propagation by cuttings or layers,
is adopted, and the plants of course have to be potted separately, so as
to be in a removable state, the following simple plan may be adopted, and
will be found to combine all the advantages and conveniences attending the
use of pots, with the avoidance of the evils of transplantation, &c. The
plan referred to, consists in the employment of turf or peat, so contrived
as to supply the place of pots, and which of course at the time of
planting is simply placed, along with the plant it contains, at once into
the soil, without in the least disturbing the roots, which, growing
through the substance of the turf, extend beyond it in all directions into
the free soil provided for them. These turf pots are made of spongy,
fibrous turf--whether loamy or peaty is not material, provided it is full
of fibre, so as to admit of being readily traversed by the roots. The
grassy surface is evenly removed, and the under-turves are cut three or
four inches in thickness, and are then divided into squares of about three
inches across. The centre of each of these little squares is taken out by
means of an iron scoop, such as that represented in the annexed sketch;
and this is then filled up with soil, and the plant, or seed, or cutting,
or layer, inserted as if it were into an ordinary flower pot. It will be
obvious that by this plan, every plant is independent and perfectly
removable--thus securing the convenience of sowing or planting and rearing
the plants in pots during their earliest stages: on the other hand, at the
time of planting out permanently, the plant, turf, and all being set
carefully into the soil, no check is sustained, because the roots remain
undisturbed, and may, as they advance, penetrate through the turf into the
prepared soil which surrounds them; in this way the advantages of sowing
or planting at the very first in the position the plants are intended to
occupy permanently, are secured.
[Illustration]
This plan of sowing seeds, or of planting young plants intended for
transplantation, into pots made of turf, is not only applicable to
cucumbers, but might be very extensively adopted in the case of annuals
and half hardy plants raised in frames, during the spring, in large
quantities for the flower garden. In these cases, however, as the quantity
that could be reared within a given space would be an object, the turves
should be as small as possible in their lateral dimensions--a bore of two
inches and a half, with half an inch on each side, thus making the
diameter three inches and a half, would be found convenient in this
respect. For cucumbers, however, or when the plan was applied to any
special object, a larger size might be employed, which would allow of the
plants attaining a larger size before it would be necessary to place them
in their permanent positions.
_On Watering the Soil._
In the diagram at p. 18, and the description of it at p. 20, I have
indicated and recommended a plan of moistening the soil by pouring water
down beneath the soil: this was to be done by the help of tubes provided
for the purpose. The soil was supposed to rest on the top of the hot
water-tank, which was to supply bottom heat; and immediately beneath the
soil, a layer of open rubble was proposed to be placed, among which the
water applied might find its way, and gradually moisten the superincumbent
soil. Mr. Hunter, gardener at Mawley Hall, in detailing[3] his sixteen
years' experience in tank-heating, has in great measure corroborated
these views; and as his corroboration of the plan I have recommended,
embodies some useful hints, I will quote the substance of his remarks:--"I
had a pit erected, thirty-eight feet long, seven and a half wide, divided
into four compartments, for growing melons and cucumbers, with a tank
extending the whole length of the pit, six feet wide and six inches deep.
Across this I put larch spars, and upon them turves, with the grassy side
downwards, and on them the soil for the melons and cucumbers. The plants
grew and did well for a time, but they were of short duration in
comparison with the dung-bed. Instead of the moisture ascending through
the soil as I expected, I found that the heat from the tank dried the
turves and soil next to them as dry as dust, and that there was no such
thing as obtaining a moist heat from hot water without the soil was in
contact with it. Next year I put broken stones upon the spars, and turves
upon them, and made my arrangements so that I could occasionally run water
in the tank to wet the turves and the soil next them. This was an
improvement; and I went on prosperously for some years, till the spars
began to decay. I then had iron bars put across, and two of the
compartments covered with squares, a foot in diameter, and one inch thick;
the other two with slates; both slates and squares jointed with Roman
cement, to prevent the soil from getting into the tank, as I had found the
inconvenience of it when using the spars. I put some broken stones upon
the covers, and turves upon them, and then the soil. Here my original
difficulty occurred; the soil next the covers got too dry, and to moisten
it from above was impracticable, without making the soil a complete
puddle, which would have stopped the healthy growth of the plants. To
remedy this, I put six small earthen pipes into each division, the one end
resting upon the tank covers, the other standing up above the soil. When I
found by the watch sticks that the soil was getting dry, I poured water
down the pipes through a tin funnel which I had made on purpose; this
spread itself over the surface of the tank covers, and diffused a gentle
moisture to the soil, so congenial to the growth of plants. This was a
move in the right direction. I then thought that it would be better to
pour the manure water down upon the tank covers, which I have done since.
I found the broken stones over the tank covers troublesome; they were also
a harbour for wood-lice. I now use only a layer of leaves next the covers,
and they are cleared out with the soil."
_On Atmospheric Humidity._