the manner recommended, and upon the necessary amount of the expense. My
gardener is an extremely simple labourer, he does not know a letter or a
figure; and he never saw a Pine plant growing, till he saw those of
which he has the care. If I were absent, he would not know at what
period of maturity to cut the fruit; but in every other respect he knows
how to manage the plants as well as I do; and I could teach any other
moderately intelligent and attentive labourer, in one month, to manage
them just as well as he can: in short, I do not think the skill
necessary to raise a Pine Apple, according to the mode of culture I
recommend, is as great as that requisite to raise a forced crop of
potatoes. The expense of fuel for my hot-house, which is forty feet
long, by twelve wide, is rather less than sevenpence a-day here, where I
am twelve miles distant from coal-pits: and if I possessed the
advantages of a curved iron-roof, such as those erected by Mr. Loudon,
at Bayswater, which would prevent the too rapid escape of heated-air in
cold weather, I entertain no doubt, that the expense of heating a house
forty-five feet long, and ten wide, and capable of holding eighty
fruiting Pine plants, exclusive of grapes or other fruits upon the back
wall, would not exceed fourpence a day. A roof of properly curved iron
bars, appears to me also to present many other advantages: it may be
erected at much less cost, it is much more durable, it requires much
less expense to paint it, and it admits greatly more light.” _Hort.
Trans._ iv. 72.
Mr. Knight adds, “I have not yet been troubled with insects upon my Pine
plants (having only had nine plants for about as many months), and have
not, of course, tried any of the published receipts for destroying them.
Mr. Baldwin recommends the steam of hot fermenting horse-dung: I
conclude the destructive agent, in this case, is ammoniacal gas; which
Sir Humphry Davy informed me he had found to be instantly fatal to every
species of insect; and if so, this might be obtained at a small expense,
by pouring a solution of crude muriate of ammonia upon quick-lime; the
stable, or cow-house, would afford an equally efficient, though less
delicate, fluid. The ammoniacal gas might, I conceive, be impelled, by
means of a pair of bellows, amongst the leaves of the infected plants,
in sufficient quantity to destroy animal, without injuring vegetable
life: and it is a very interesting question to the gardener, whether his
hardy enemy, the red spider, will bear it with impunity.”
[Illustration: 18]
In the year 1820, in June, Mr. Knight had such a house as he has hinted
at, erected. Its general appearance (fig. 18.), is simple, and the roof
admits as much light, as any roof that can be constructed in the present
state of knowledge, in the combination of wrought iron and common glass.
[Illustration: 19]
The plan of this house, or pit (fig. 19.), is fifty feet in length, and
ten feet wide; the furnace (_a_) is placed at one end; the flue
proceeds from it directly to the front parapet (_b_), and passing along
close under it to the opposite end, there terminates in a chimney (_c_).
Instead of a pit, a curious stage is constructed, by forming cross walls
(_d_), or rather piers, connected by arches, and finished by a gradation
of flat surfaces, or steps, on which the pots are placed, so as to stand
as near the glass as possible (fig. 20.)
[Illustration: 20]
Air is admitted by shutters, which open outwards, immediately under the
stone plinth of the parapet (fig. 20. _a_), in which the lower ends of
the iron bars are fixed; and allowed to escape by similar shutters,
opening outwards, immediately under the stone coping of the back wall
(_b_), in which the upper ends of the same bars are leaded in. The path
behind is on a level with the exterior surface; the width of the cross
walls the length of a brick, or nine inches, and they are finished with
foot tyles; the width between them is about fifteen inches, by which
means, any ordinary sized person may pass from the back path to the
front flue, and water or examine the plants on each side.
This house being finished, was immediately stocked with Pines, some
figs, and various other plants, all of which, Mr. Knight stated
verbally, in May 1821, to various members of the Horticultural Society,
succeeded admirably; but by neglect of the gardener, or rather labourer,
who attended them, they were killed by an over-heat in Mr. Knight’s
absence from home.[1]
[1] The poor man had probably overheated himself, and comparing by
his feelings the temperature of the Pinery with his own, found the
latter much in its usual state; not knowing “a letter or a figure,”
of course, he could not take a hint from the thermometer.
The house was again stocked with plants, which Mr. Knight, in a paper
read to the Horticultural Society, in November last (1821), stated to be
in a most thriving condition; and a friend of ours who had made an
extensive gardening tour in the North and West of England, and who saw
the Pine plants at Downton Castle, also in November, declares they
appeared the most magnificent he had seen on his journey; “the plants,”
he says, “were stocky, and the leaves long, broad, and green; the
largest were in pots fourteen inches in diameter, and their leaves
reached to the glass.”
In the paper alluded to, Mr. Knight goes on to say, “I possess more than
sufficient evidence to enable me to assert with confidence, that, in the
culture of the Pine Apple, the bark bed, or other hot-bed, if the plants
be plunged into it, is worse than useless, after the scions, or crowns,
have emitted roots; and that the Pine Apple, when treated in the manner
I have recommended, is a fruit of most extremely easy culture.
“It is contended, in favour of the bark-bed, that the soil in
inter-tropical climates is warm, and that the bark-bed does no more than
nature does in the native climate of the Pine Apple. And if the bark-bed
could be made to give a steady temperature of about ten degrees below
that of the day temperature of the air in the stove, I readily admit
that Pine plants would thrive better in a compost of that temperature,
than in a colder. But the temperature of the bark-bed is constantly
subject to excess, and defect, and I contend, and can prove, that the
above-mentioned temperature is very nearly given in my stove. For the
temperature of the day being about 90° or 95°, and that of the night
70°, the mould in the pots will necessarily acquire nearly the
intermediate temperature of 80°. It is true, that two disturbing causes
are in action; the evaporation from the mould, and porous surface of the
pots, and the radiant heat of the sun. But these causes operate in
opposition to each other, and probably nearly negative the operation of
each other, as far as respects the temperature of the mould in the pots.
“A very great number of gardeners have within the last twelve months
visited my garden. Some of these were at once convinced of the
advantages of the mode of culture which they saw; others have paid a
second, or third visit; but every one has ultimately declared himself a
zealous convert. I have never yet seen plants of the same age equally
strong, nor any producing fruit better, nor indeed so well swelled; nor
any equal in richness and flavour. But I have never taken off, nor
shortened a root, nor taken any other measures to retard the period of
fructification, with the prospect of obtaining larger fruit; and my
plants have almost always showed fruit when fourteen or fifteen months
old, though propagated from small and young suckers, or crowns. A great
part of my Queen Pines (I have hitherto scarcely ever cultivated any
other varieties) have, however, at that age, shown fruit with eight, and
some with nine rows of pips; and I often see fruit of less weight
growing upon plants of nearly double that age. Whether I shall be able
to retard the period of fructification, or not, I have yet to learn; but
I believe, I shall succeed by crowding my plants close together, so that
each may receive less light.
“Pine plants will, however, grow perfectly well in composts of different
kinds; but I have found that they have succeeded best when the materials
have been fresh, and retaining their organic form, particularly if the
pots be large, relatively to the size of the plants, which, I think,
they always ought to be, for the mode of culture recommended. I have
used, with advantage, the haulm of beans cut into lengths of about an
inch.
“Very contrary to the conclusions which I should have been led to draw
from writings upon the culture of the Pine Apple, I have constantly
found that my plants succeed best in the part of my house where the flue
first enters, and where the temperature is very high, varying from about
85° to 105°, and the air excessively dry. I have pointed out this
circumstance to every gardener, whom I have seen in my house, and all
have expressed their astonishment at the circumstance. I expected that
this excess of heat would have occasioned the plants to show fruit
prematurely, but this has not occurred in a single instance. What would
be the quality of the fruit, if it were to be ripened in so high a
temperature, I have not yet had an opportunity of knowing.
“In raising young plants, I have deviated from the ordinary mode of
practice by breaking off the suckers when very young; that is, when they
are not more than four or five inches long. The fruit is much benefited
by their absence; and the cuttings, if placed very close together in a
hot-bed, are made to emit roots with little trouble, and afford better
plants than they do when they are suffered to remain long upon the
parent stem. When the whole are removed at an early period, one or more
very strong suckers usually spring out below the level of the soil; and
from these, suffering only one to remain attached to the parent stem,
and preserving the roots as entire as possible, I have propagated with
much advantage, and have obtained plants which showed fruit strongly at
seven months, dating from the period at which the sucker appeared, like
a strong head of asparagus, at the surface of the soil.
“The success of my experiments, in the first house which I erected, (and
to which the foregoing account exclusively refers,) led me to erect
another house (figs. 18. 19. and 20.) in the summer of 1829. In this I
attempted to obtain the greatest possible influence of light, and
command of solar heat; inferring, from having observed Pine Apples to
ripen tolerably well with very little light, that I should be able to
ripen them in perfection late in the autumn, and early in the spring,
particularly at the latter period, in which, alone, I set a very high
value upon the species of fruit. The height of the back wall (fig. 20.)
of this house is eight feet six inches, and that of the front wall is
one foot six inches, and its breadth ten feet, inside measure, with an
iron curvilinear roof, (fig. 18.) of the kind of bar invented by Mr.
LOUDON, of Bayswater. This house is fifty feet long, (fig. 19.) and
capable of containing two hundred fruiting Pine plants. The curvature of
the roof rises just one foot in twelve. The glass is laid in a
composition of two parts white lead, with oil, and three of flint sand,
and the overlaps of the glass are closely filled with the same material.
It is, consequently, very nearly air-tight; and no means are given for
the air to enter, or escape, except by apertures immediately under the
copings of the front and back wall, (_a_ and _b_, fig. 20.) which can
be efficiently closed at any time. It is, consequently, an instrument of
very great power, and requiring, of course, much attention to
ventilation: of which I had rather a lamentable proof in the last
spring, when my plants were all burned, and spoiled in a few hours; the
person who had the care of them having left them in a bright day closely
shut up. The fault was not, however, in any degree in the house, for the
plants were, previously, much the strongest, and the best I ever saw;
and I believe, they would have afforded most beautiful fruit. I
furnished the house again with plants as expeditiously as I could,
chiefly in July; and I have since kept the temperature of it nearly
between 70° and 95°, with a wish to make the plants show fruit and
blossom in the present month (October.) In this, I have in part
succeeded, though many of my plants have flowered a fortnight or three
weeks sooner than I wished. The fruit is swelling well, and, I believe,
will receive sufficient light through the winter to enable it to ripen
in much perfection. The excellence of a few Pine Apples, which ripened
in this house in the last winter, leads me almost to doubt, whether the
fruit in it will not ripen better, early in the spring, than in the
middle of the summer, for I have observed that this species of plant,
though extremely patient of high temperature, is not, by any means, so
patient of the action of very continued bright light, as many other
plants: and much less so than the Fig and Orange tree: possibly, having
been formed by nature for inter-tropical climates, its powers of life
may become fatigued, and exhausted by the length of a bright English
summer’s day in high temperature. Being a plant of low stature, nature
has also probably given it the power to ripen its fruit and seed, in the
shade of other plants, in its native climate; and I discovered in the
last summer, that it possesses the power to ripen its fruit perfectly in
a lower temperature than I previously thought it capable of growing in.
“In the month of June, I gave a couple of Pine plants, which had shown
fruit at six months old, and were of small size, and no value, to a
child of one of my friends, to be placed in a conservatory, in which no
fires were kept during the summer. In July, a storm of hail destroyed
nearly, or fully, half the glass of the conservatory; and its
temperature, through the summer and autumn, had been so low, that the
Chasselas grapes in it were not ripe in the second week in September. In
the second week of the present month (October) one of the Pine Apples
became ripe, having previously swollen to a most extraordinary size,
comparatively with the size of the plant; and upon measuring accurately
the comparative width of the fruit, and of the stem, I found the width
of the fruit to exceed that of the stem in the proportion of seven and
three-quarters to one. The fruit had, of course, been propped during all
the latter part of the summer, the stem being wholly incapable of
supporting it. The taste and flavour of this fruit were excellent, and
the appearance of the other, which is not yet ripe, and is of a larger
size, is still more promising. I purpose to profit by this result in the
next summer; and I hope to be able to communicate some further
information to the Society in the autumn. I feel perfectly confident,
that if the roots of these plants had grown in a hot-bed of any kind,
their sap would have been impelled into other channels; and that their
fruit would not have attained, in any degree, the state of perfection
which I have described.”
This is the latest printed account of Mr. Knight’s experiments on the
Pine Apple. It would be premature to draw any general conclusions in so
early a stage of their progress, and might excite prejudice to
anticipate the final result. That the Pine plant will grow and thrive
without what is technically called bottom heat, is an obvious truth,
since no plant in a state of nature is found growing in soil warmer than
that of the superincumbent atmosphere. But to imitate nature, is not
always the best mode of culture; for the more correct the imitation, the
less valuable would be the greater part of her products, at least as far
as horticulture is concerned. What would our celery, cabbage, and apples
be, if their culture were copied from nature? Though the Pine Apple will
grow well without bottom heat, it may grow with bottom heat still
better; and though the heat of the earth, in its native country, may
never exceed that of the surrounding atmosphere, it does not follow that
earth heated to a greater degree may not be of service to it, in a state
of artificial culture. But admitting, for the sake of argument, that the
Pine plant could be grown equally well with, as without bottom heat;
still it appears to us that the mass of material which furnishes this
heat, will always be a most desirable thing to have in a Pine stove, as
being a perpetual fund of heat for supplying the atmosphere of the
house, in case of accident to the flues or steam apparatus. Besides it
appears from nature, as well as from observing what takes place in
culture, that the want of a steady temperature and degree of moisture at
the roots of plants is more immediately and powerfully injurious to them
than atmospheric changes. Earth, especially if rendered porous and
spungelike by culture, receives and gives out air and heat slowly; and
while the temperature of the air of a country, or a hot-house, may vary
twenty or thirty degrees in the course of twenty-four hours, the soil at
the depth of two inches would hardly be found to have varied one degree.
With respect to moisture, every cultivator knows, that in a properly
constituted and regularly pulverized soil, whatever quantity of rain may
fall on the surface, the soil is never saturated with water, nor, in
times of great drought, burnt up with heat. The porous texture of the
soil and sub-soil being at once favourable for the escape of
superfluous water, and adverse to its evaporation, by never becoming so
much heated on the surface, or conducting the heat so far downwards as a
close compact soil.
These properties of the soil relatively to plants can never be
completely attained by growing plants in pots, and least of all by
growing them in pots surrounded by air. In this state, whatever may be
the care of the gardener, a continual succession of changes of
temperature will take place in the outside of the pot, and the compact
material of which it is composed being a much more rapid conductor of
heat than porous earth, it will soon be communicated to the web of roots
within.
With respect to water, a plant in a pot surrounded by air is equally
liable to injury. If the soil be properly constituted, and the pot
properly drained, the water passes through the mass as soon as poured on
it, and the soil at that moment may be said to be left in a state
favourable for vegetation. But as the evaporation from the surface and
sides of the pot, and the transpiration of the plant goes on, it becomes
gradually less and less so, and if not soon re-supplied, would become
dry and shrivelled, and either die from that cause, or be materially
injured by the sudden and copious application of water.
Thus, the roots of a plant in a pot surrounded by air, are liable to be
alternately chilled and scorched by cold or heat, and deluged or dried
up by superabundance or deficiency of water, and nothing but the
perpetual care and attention of the gardener to lessen the tendencies to
these extremes could at all preserve the plant from destruction.
To lessen the attention of the gardener, therefore, to render the plant
less dependent on his services, and, above all, to put a plant in a pot
as far as possible on a footing with a plant in the unconfined soil,
plunging the pot in a mass of earth, sand, dung, tan, or any such
material, appears to us a most judicious part of culture, and one that
never can be relinquished in fruit-bearing plants with impunity. Even if
no heat were to be afforded by the mass in which the pots were plunged,
still the preservation of a steady temperature which would always equal
the average temperature of the air of the house, and the retention, by
the same means, of a steady degree of moisture, would, in our opinion,
be a sufficient argument for plunging pots of vigorous growing,
many-leaved, or fruit-bearing plants.
Such are the observations that we think may be made relatively to Mr.
Knight’s plan, without prejudice to whatever new lights he may throw out
on the subject. Had it been brought forward by a less eminent
horticulturist, it would not have claimed so much attention, as the plan
of growing Pines without bottom-heat is generally considered to have
been tried first by M. Le Cour, and subsequently by various others, and
abandoned. In Mr. Knight’s hands, however, whether it fail or succeed,
it is certain of doing good, by the observations it will elicit from
the fertile and ingenious mind of so candid and philosophical a
horticulturist.
Sir William Edward Rous Boughton has erected a house or pit at Downton
Hall, similar to that of Mr. Knight, but rather wider.[2] Pines are
grown in it on Mr. Knight’s plan, but the plants were not in a thriving
state in November last. Charles Holford, Esq. of Hampstead, is also a
disciple of Mr. Knight as to the culture of this fruit, but he has not
yet been very successful.
[2] The roofs, both of this house and that of Mr. Knight, were
furnished by Messrs. W. & D. Bailey, of Holborn, London.
SECT. II.
_Of other Improvements in the Culture of the Pine Apple, by
different persons._
We shall first notice the improvements which respect bottom-heat, and
begin with noticing an attempt made by Mr. Thomas Jenkins, of the
Portman Nursery, London, to warm both the pots in which the plants are
grown, and the air of the house, by the heat generated by fermenting
stable-dung placed in a vault beneath.
It is only within the last three years that Mr. Jenkins has begun to
grow the Pine Apple to any extent; he brings forward the plants in
hot-beds and deep frames, inclosing beds of tan, and heated by linings
of dung. As an economical part of the construction, we may mention that
he substitutes wattled hurdles for the lower part of the frame, in
contact with the tan, by which means a saving in the first cost is
effected, and the heat of the dung penetrates much more readily to the
tan.
[Illustration: 21]
Most of the plants are fruited in these pits, but some are fruited in a
house, (_fig. 21._) which “though furnished with flues, yet these have
been very little used. The heat imparted to the plants is produced by
the fermentation of stable-dung in a pit below the plants, the top of
which is covered by tiles supported by iron rafters, with the joints
closely cemented, to prevent the passage of steam into the house. The
pots are neither bedded in tan, nor in mould, but stand on the tiles,
and the interstices between them warm the air of the house.”
[Illustration: 22]
The dung is managed as in West’s pit (_fig. 22._), but with the addition
of being watered after it is thrown in, which is found to promote
fermentation, and the intensity of the heat.
One of the earliest instances of steam being used as a bottom-heat with
which we are acquainted, was that by Mr. Butler, gardener to the Earl of
Derby, at Knowlesly, near Liverpool, in or about 1792. It had been used
twenty years before, but chiefly for other purposes. Speechly, in 1796,
knew only two instances in which steam was applied as bottom-heat; and,
with M’Phail, does not think it will finally answer as a substitute for
tan. Instances in which it is adopted, are now much more numerous; but
time sufficient has not elapsed, and the opinions of gardeners are yet
too unsettled on its merits to enable us to recommend it for adoption in
general practice. For heating the atmosphere of hot-houses, there seems
little (or at least much less) doubt of its being preferable to
fire-heat.
Count Zubow, at St. Petersburg, employed steam to heat a pit or cistern
of water, over which, at about three inches distance, a frame, covered
with faggots, was placed, and on this was laid the earth, in which his
Pines and other exotics were planted without being in pots. The plan is
said to have succeeded, and a wholesome temperature to have been
obtained and communicated to the mould above the faggots.
Mr. Gunter, as before observed, (Chap. IV. sect. 13.) had already tried
the use of steam as a bottom heat without success.