is that the structures which we devote to the cultivation of such plants
as the Cucumber, which are naturally habituated to an eastern clime,
should be so designed, as to offer the least possible obstruction to its
entrance: how important, too, that the glass we employ, which in its
purest state, offers considerable obstruction, by refracting the rays of
light, should be as transparent and untarnished as possible, so as to
admit them as perfectly as can be practicable; instead of which, it is too
often disfigured by an accumulation and deposit of filth, which, to say
the least, must materially diminish their force: how important, moreover,
that whatever coverings it may be necessary to employ during the night to
prevent the outward radiation of heat, should be speedily removed in the
morning, and kept off as long as they safely may be, in order to permit
the inward radiation of light. When these matters are all duly attended
to, our climate, at least during the winter, still offers obstruction
enough to our success, in its mists, and fogs, its long dark nights, and
dismal cloudy days, and therefore wisdom would teach us, to avail
ourselves of all which we can grasp, by a course of untiring assiduity,
and attention to such apparently trifling matters as these.
The pruning and training of the plants, are operations, to which it will
be necessary to direct attention; and in the performance of which, the
circumstances which may have any influence upon them, as well as the
object in view, must be taken into consideration. The plants being
intended to occupy a surface of trellis-work in a line nearly parallel
with the glass, it will be requisite to train their primary shoots to a
sufficient length to reach from the soil to the trellis, before they are
what is technically called "stopped;" this operation, by removing the
central bud, or axis of developement, induces the buds which are latently
formed at the nodes of the branches, to push forth and become the axes of
further extension: two or three of the strongest of these lateral shoots
situated towards the top of the stem, should be retained, and trained on
the trellis in a direction towards the top of the house; these shoots
should be placed about 18 inches from each other, and when they have
reached about one-third of the length of the trellis, they also should be
stopped, and thus several more lateral shoots will be produced. The
uppermost strong shoot should in each case, be still trained in the same
upward direction, and the others must be disposed in the most convenient
form in the space between the main branches: these, that is the young
lateral shoots, if they do not shew a fruit blossom at the second joint or
leaf from the main branch, must be stopped, and the young shoot thus
induced to push forth, will in all probability have fruit at the first
leaf; if not, it must be stopped at _every leaf_ as it extends, until
fruit is observed. The upper portion of the branch after having extended
about one-third further up the roof, should be submitted to the same
process, and this must be again repeated until the whole of the trellis is
covered.
No reference has yet been made to the treatment of those lateral branches
where the young fruit are perceived: these should be permitted to grow
until the blossoms have expanded; and then, after this, they should be
stopped at the leaf next beyond the fruit blossoms. By permitting them to
grow until the flowers have expanded, the attraction of the growing branch
will continue to draw up a regular supply of nutriment, part of which will
be devoted in its course, to assist the developement of the blossoms; and
besides the advantage of the growing point acting thus as a sucker to draw
onwards the vital juices towards the young fruit, it will act also as an
outlet, to drain off what would otherwise be superabundant and dangerous
to these tender organs of reproduction. After the flowers have expanded,
this danger does not exist to so great an extent, the infant fruit have
new and important functions to perform, which are peculiarly their own;
and these call for a greater supply from the nutritive organs of the
plant: the stopping of the branch therefore, is the means of throwing in
this increased supply of food; but those who can most fully appreciate the
delicacy of the functions performed by the plant at this stage of its
developement, will most fully value the suggestion not to stop back the
growing branch _all at once_, but to do it by successional, though not
distant operations. The leaf which is directed to be left above, or beyond
each fruit, will serve, both as a reservoir, to receive all the
superabundant food, which may either be induced or impelled upwards; and
also, as a labaratory where this food will become purified and changed by
its exposure to atmospheric influence, amongst the lax tissue; and whence,
an appointed portion will be returned, and devoted by a process of
assimilation, to aid in the extension of the plants.
This system of pruning, with reference both to the barren and the fruitful
branches, must be continued, whilst these continue in a vigorous and
healthy condition; but when any symptoms of decay or of expended powers,
are perceived, they should be pruned quite away, and young ones encouraged
in their stead. All the pruning which has been spoken of, except the
occasional removal of a main shoot, should be done at a sufficiently early
period of growth, to admit of being effected by means of the thumb-nail;
for like all other plants, Cucumbers are much best treated, when whatever
pruning they may require, is done at that stage of growth, when the least
amount of trouble and labour is required to perform it. Pruning is not
under any circumstances a natural process, and when we have recourse to it
in artificial cultivation, it is only an expedient, which is rendered
necessary by the limited space, within which it becomes necessary to
confine the extension of the plants; and since this is the case, it is far
better to remove a portion of any plant, at an early period of its
growth, and thus to economize its vital energies, rather than to suffer
them to be expended, and the supply to become exhausted through a
superfluous developement, and then to deprive it of those very organs, by
the action of which, the expenditure would be again recompensed to the
vital energies.
CHAP. V.
ON THE NATURE, AND COMPOSITION OF THE SOIL.
Plants absorb fluids through the extremities or spongioles of the roots,
and it is thus that those portions of the substances which serve them as
their food, and are derived from the soil, are carried into their system,
in a state of solution: these spongioles are not strictly to be regarded
as analogous to the mouths of animals, for they are not provided with
openings, and cannot imbibe even the most impalpable powders; their action
seems to be more analogous to that of the lacteals in animals, for these,
as well as spongioles, serve to convey fluids only. These considerations
render it necessary, that in the composition of soil for the growth of
plants, the following important points should be held in
consideration;--it should contain a sufficient ratio of organizable
matter, that is of substances which can be rendered available as food to
the plants; it should readily absorb fluids, since it is only when in a
state of solution, that food can enter into the structure of the plants;
it should be sufficiently retentive to avoid the risk of injury by reason
of the evaporation, which takes place to a very great extent, when too
great an abundance of silica is present, or when more than a due degree of
porosity exists in its mechanical texture; and it should be sufficiently
permeable, to prevent any thing like excess of moisture, by stagnation.
Soils composed either principally, or almost entirely of heath soil, or of
vegetable mould, although very highly recommended for the growth of the
Cucumber in winter, are nevertheless objectionable when applied alone, as
will be evident if the foregoing principles are taken into view: it cannot
however be assumed that the plants will not grow in these soils, for they
grow vigorously for a period; neither can it be asserted that such soils
do not contain the qualities which are necessary to administer to the
nutrition of plants, for it is scarcely possible to conceive any
substances which are more nutritious, or whose application in this respect
is more effectual; but they are objectionable, in consequence of their
becoming soon expended, and failing to maintain for any length of time, an
equable degree of moisture. The cause which tends to produce this effect,
is the porosity, or the want of mechanical combination in the texture of
the soil; which being highly favourable to evaporation, is liable to
render it speedily, and very materially dry, when exposed to the influence
of powerful solar heat: the frequent application of water, does not
entirely obviate the objection, for even when so applied, it soon becomes
again evaporated, and thus tends to deteriorate the soil, and decrease its
fertility; this it does, by taking up much of the soluble matter contained
in it, and conveying it by evaporation into the atmosphere, instead of its
being taken up by the roots whilst in a fluid state, and applied to the
plant as a means of nutrition: when it is thus conveyed to the atmosphere,
the leaves though they are enabled to take up a portion of their food from
thence, are still incapacitated to do so fully, and hence, much of the
fertilizing properties of the soil, is carried off by the first current
of air which passes through the structure; and the plants decline by
reason of starvation, though they had been seated in the midst of plenty.
The soil which I should recommend for the growth of the Cucumber, would be
composed of ingredients, capable of supplying a sufficient portion of
vegetable food; of retaining a due portion of moisture, when placed under
powerful evaporation; and of securing the free passage of water through
its mass: the former of these conditions would be secured, by the use of
mould from the decaying leaves of trees, in the proportion of about
three-eighths; the latter would be ensured, by employing about one-fourth
part of turfy heath mould, and one-eighth part of clean coarse sand; and
the remaining quality, would result by combining these ingredients with
one-fourth part of good turfy loam. The preparation of this soil should
take place in the dry weather of the summer months, just previous to its
being used, so that it can be frequently turned and mixed, without
incurring the danger of reducing it to an adhesive consistency, which
would at once render it ungenial for the roots of plants: the turfy
portions both of the loam and heath soil should be piled up reversely,
until the herbage and roots of the grass, become partially decayed; when
required for use, it should be chopped into pieces of from two to four
inches square, by the spade, and then adding the other ingredients _in a
rough state_, the whole should be well mixed, without sifting, or any
other mechanical operation which would have the effect of destroying its
open texture. It should always be prevented from becoming saturated with
water; and moreover, should never be applied to the roots of plants which
are growing in a warm medium, without having been previously submitted to
a high temperature, for a sufficient length of time, to have absorbed at
least an equal degree of heat, with that in which the plants might be
already growing.
The admixture of charcoal with the soil, is said to be a means of adding
to its nutritive qualities. Charcoal, which is nearly pure carbon, may be
supposed continually to give off a portion of this gaseous substance
during its decomposition, and this uniting with a portion of the oxygen
contained in the air, would furnish a supply of carbonic acid gas, to the
atmosphere immediately about the plants. It should however be borne in
mind, that charcoal, is a substance whose decomposition except under the
influence of heat, proceeds very slowly indeed, and therefore its chemical
influence must not be overrated: doubtless however, the small portion
which does combine with the oxygen of the air, is directly beneficial to
the plants; for it is a function of the vegetable kingdom by the action of
their leaves, when under the influence of light, to decompose carbonic
acid, the oxygen of which is liberated, and the carbon fixed in the living
tissue. It is therefore probable that a supply of carbonic acid,
artificially maintained about the leaves and stems of plants, may be
beneficial to them, by furnishing them directly with a portion of carbon,
which they cannot absorb in a seperate state. When the charcoal is made
from twigs, and the small branches of trees, its decomposition is often
more rapid, than when it is obtained by the usual course of manufactering
it: if the latter kind of charcoal is employed, it should be broken into
pieces of a small size; and in ordinary cases, it should not be used in
larger proportion than with about twice its bulk of soil, with which it
should be intimately blended.
Besides its chemical action, which is probably beneficial, charcoal has a
decidedly advantageous mechanical action in the composition of soils, and
this is of a twofold nature:--first, in common with any similar
materials, it renders the soil "open," and thus effectually favours the
free passage of water through its mass: secondly, it serves as a perpetual
reservoir of moisture in the soil, for in consequence of its being
extremely porous, it imbibes a great quantity of water, by its force of
attraction, and this it parts with slowly to the soil; in this way, there
is no doubt that its action is most salutary. Probably a few pieces of
charcoal placed perpendicularly in the soil, and kept continually _wet_,
by the action of some little capillary contrivance, would serve as the
best possible means of conducting moisture, and distributing it to the
roots of plants.
It will be observed that the application of dung, in any way whatever, has
not been recommended; neither do I consider it to be at all requisite, or
desirable, in the culture of winter Cucumbers: luxuriance is not a
consummation which it is at all desirable to attain to, a moderate, well
matured growth, being far preferable; and as some care is supposed to be
used to provide suitable soil, it should be of such a nature as to possess
the properties, which are requisite to effect the desired end. Dung
containing as it does fertilizing properties, may do well to renew the
fertility of exhausted soils, which may have been under a long course of
cultivation; but it is questionable, whether it ought to be admissable to
any extent in pot culture, or in the growth of forced plants, in
preference to a supply of wholesome unexhausted natural soil.
A very great objection to the use of dung when applied in a solid state in
the composition of soils, consists, in its being presented to the roots of
plants, not only in the advanced periods of their existence, but equally
so, during the early stages of their growth; here must be an error, for
infants, whether they belong to the animal or vegetable kingdom, are
certainly not capacitated to appropriate the same kind of food, in the
same proportion, as adults. If only a small portion of soil is at first
employed, and portions more and more enriched, are from time to time
added, as the roots may extend, we are still liable to stumble on an
objection, almost as important, though of a somewhat different nature; for
we can in that case scarcely fail to injure the spongioles of the roots in
a greater or less degree, and the injury thus sustained, will consequently
act as a check in the progress of their developement. These considerations
seem at once to mark the propriety of applying liquid manures in highly
artificial cultivation; they can be supplied in this state, when the
plants are in such a mature and advanced state of growth, as from time to
time to require their aid; and their fertilizing properties being held in
solution by the fluid medium in which they are conveyed, they are just in
the condition to be taken up at once by the rootlets. It must still
however be recollected, that whilst even impalpable powders cannot as such
be made to minister to the nutrition of plants, so neither can gross
liquids effect this purpose: it is clear limpid fluids, only, which can be
received by the delicate spongioles, and therefore the so-called manure
water, when applied of the consistency of mud, is not only in an unfit
state to effect its purpose, except by the addition of a more bountiful
supply of pure liquid, but it is also liable to act injuriously by reason
of the concentration of the strength or powerful qualities of the manure,
and by counteracting the open texture of the soil. Manure water,
therefore, from whatever source it may be derived, though not necessarily
a colourless, should without question, be a limpid fluid; if otherwise
applied, it will at once destroy one of the best qualities a soil can
possess, viz. porosity.
CHAP. VI.
ON THE APPLICATION OF MOISTURE.
From what has been stated in the preceeding chapter, it will be
sufficiently evident, that a supply of water is required as a component of
the soil, in which all plants are grown, in order to enable them to draw
from it, other components, which form their food; and that, as it is
necessary for them continually to take up a portion of this food, so is it
necessary, that moisture should be continually present, in order to render
it available by them.
Among other conditions to which the operation of applying water to the
soil should be subjected, there are some which are specially important: it
should never be either applied in _excess_, or unduly withheld; nor should
it ever be applied when of a temperature below that of the atmosphere in
which the plants to whose roots it is applied, are growing at the time of
its application.
There is a liability of applying water in excess, when the particular
stage of growth, the peculiar state of the weather, or the season of the
year, are not duly regarded: thus, an adult plant will consume more water
than an infant plant; and any plant, will decompose a larger quantity of
water, in sunny weather, when evaporation is going on briskly, than in
cloudy weather, when it is scarcely perceptible; again, in the summer
season, a much larger quantity will be appropriated, than in the winter.
Water has been applied in excess, whenever the soil becomes soddened or
saturated therewith; but great as this evil is, it is equalled in its
injurious effects, by falling into the opposite extreme, and withholding a
quantity sufficient to render the constituents of the soil, available as
food to the roots of plants placed in it.
The necessity of applying water, of a temperature equal to that of the
soil, is rendered evident by a reference to the natural conditions by
which the soil is watered. In a small and nearly globular form, the water
gathered up by the action of the sun, and forming the clouds above us, is
precipitated through the atmosphere, and there its temperature becomes
equalized or assimilated with that of the medium through which it has been
passing; and although in our own latitude, we perhaps fail to discover any
material degree of warmth in the drops of rain as they fall, yet in
eastern climes, we cannot but imagine, that after having been submitted in
the thin strata of the clouds to the action of the sun, they must
previously to entering the soil, have imbibed some portion of heat.
Moreover, the importance of maintaining a gentle bottom heat, at the roots
of forced plants, renders it necessary to avoid any application, which may
tend to lesson its effect, and submit the roots to any chilling influence.
The temperature of the soil is naturally above that of the atmosphere, and
as the application of moisture by exciting evaporation, has an abstract
tendency to lower the temperature, it should therefore, when applied, be
in a slight degree warmed, so as thus to increase rather than diminish the
heat contained in the soil.
As some moisture in the soil is necessary to render the food contained
therein, soluble, and available to the spongioles of the roots, so
moisture in the atmosphere is essentially necessary to assist in applying
the gaseous elements of that elastic compound fluid, to the nutrition of
plants by the action of the leaves: without moisture in the atmosphere,
the leaves and outer covering of plants would become dessicated, and the
stomatas shrivelled up and closed, so that neither the exhaling nor the
imbibing functions of the plants could then be carried on.
The moisture of the atmosphere, then must not be neglected; not only
because the healthy action of the vital organs of the plants depends on a
proper hygrometrical state of the atmosphere, but, inasmuch as it is the
readiest means both of avoiding, and when unhappily, they are present, of
destroying, many of the most destructive and troublesome insect enemies,
to whose depredations, plants are subject.
When a moist atmosphere is duly and regularly maintained, there is but
little fear need be entertained of the establishment of a colony of
insects--such as the thrip, and the red spider, which are perhaps the
greatest pests which have to be overcome in the forcing house; nor is
there a more effectual method of destroying them, than by applying a high
temperature in conjunction with an intense degree of moisture. To the want
of a balance of moisture in the composition of the atmosphere, and in the
soil, too, rather than as is commonly supposed, to an excess of it in the
former, is the appearance called mildew to be attributed; this it
occasions by checking the regular action of the perspiratory organs, and
thereby inducing an eruption of the cells of the tissue: the extravasated
sap lodging on the cuticle, affords a nidus for the germination of the
sporules of that particular fungus, which when grown, is the mildew: the
remedy consists in avoiding an irregular composition of the atmosphere, as
regards heat and moisture; and also an excess or deficiency of moisture in
the soil, so that each may be in a condition to exert its proper influence
on the constitution and developement of the plants. Canker, another
disease, to which Cucumbers are sometimes subject, appears to be produced
by too low a degree of temperature, accompanied by an excess of moisture,
both in the soil and the atmosphere, and it generally attacks those
particular parts, where any check or obstruction is offered to the flow of
the sap, such as that occasioned by a wound, or even the ramifications of
the stem: this suggests that its remedy, would consist in a due regulation
and balance of the constituents of the atmosphere, and the soil.
Moisture is generally applied to the soil by being poured directly on it,
and to the atmosphere, by means of the syringe, and the use of evaporation
troughs. When applied to the soil only from the upper surface, there is a
liability of its failing thoroughly to moisten it, and by reason of this,
together with the constant action of the heat from below, by whatever
means heat may be applied, the soil is frequently found to be dry beneath,
when the appearance of the surface might lead to the supposition that it
was sufficiently moistened.
By a reference to the sketch and description already given, it will be
seen, that a provision is there made, whereby water can be poured in
quantity _beneath the soil_, immediately on the top of the tank, whence in
the form of vapour it will rise among the soil, and thus render it
thoroughly moist; at the same time, it can be applied to the surface,
whenever it may become necessary to do so. The moistening of the
atmosphere will also be fully secured by the mode of ventilation which is
there proposed, for the air, at the same time that it is warmed, will
become charged with moisture in a ratio equal to its temperature, before
it enters the house. If it becomes requisite to admit moisture without
changing the volume of air, it can readily be effected by opening the
tubes or shafts inside the house, without opening the exterior
ventilators; and when dry heat may be required, it can be secured by
closing entirely the communication with this reservoir of moisture, and
the hot-water pipes will then radiate any quantity of dry heat that may be
required.