to be exactly suited to its nature. Hence the origin of shelter and shade, by means of
walls, hedges, or strips of jilantation; of sloping surfaces or banks, to receive more
directly or indirectly the rays of the s u n ; of soils better calculated to absorb and retain
heat; walls fuUy exposed to the south, or to the north; of training or spreading out
the branches of trees on those walls; of hot-walls; of hot-bcds; and, finally, of all. the
variety of hot-houses. Nature also suggests this part of culture, by presenting, in every
country, different degrees of shelter, shade, and surface, and iu eveiy zone diflcrent
climates.
1128. The regulation o f moisture is the next point demanding attention; for when the
soil is pulverised, it is more ctisily dried by the penetration of the a i r ; and a due supjily
of water is essential to plants, not only because it furnishes an unportant portion of thcir
food itsolij but because it serves as a medium by which they imbibe other food. In hot
weather ai-tificial supplies of water become necessaiy; as when the temperature is
increased, tho evaporation becomes greater. Hence the origin of watering by smface or
subton'ancoiis irrigation, manual supplies to the root, showering over the leaves, steaming
the surrounding atmosphere, &c. Tliis is only to imitate the dews and showers, streams
and floods of n a tu re ; and it is to be regretted that the imitation is in most countries
attended with so much labour, and requires so much nicety in the arrangement of the
means, and judgment in the application of the water, that it is but vciy pai-tially applied
by man in every part of the world, excepting, perhaps, a small district of Italy. But
moisture may be excessive ; as when plants have too much hydrogen, which they obtain
from the decomposition of water, they begin to decay. Thus from certain soils at certain
seasons, ancl from certain productions at particulai* periods of tlicir progress, it may
be necessary to carry off a great part of the natural moisture, rather than to let it sink
into the earth, or to draw it off wliere it has sunk in and injuriously accumulated, or to
prevent its falling on the crop at a l l; and hcncc the origin of surface-di'uinage by
ridges, and of under-draining by covered conduits, or gutters ; and of awnings aud other
covers to keep off the rain or dews from ripe fruits, seeds, or rare flowers.
1129. The regulation o f light is the remaining point. Light sometimes requires to be
excluded, sometimes to be modified, and sometimes to be increased, in order to improve
the qualities of vegetables; and hcncc the origin of thinning the leaves which overshadow
fruits and flowers, the shading of cuttings, seeds, &c., and the practice of blanching.
The latter practice is derived from accidents obsci'vable among vegetables in a wild
state, and its influence on thcir quality is physiologically accounted for by the obstruction
of perspiration, and the prevention of the chemical changes effected by light on the
cpidennis.
1130. To increase the magnitude o f vegetables, without reference to their quality, it is
necessary to afford them an increased supply of all the ingredients of food, distributed in
such a body of weU pulverised soil as the roots can reach t o ; and of heat and moisture :
they should also be partially excluded from the direct rays of the sun, so as to moderate
perspii'atiou; and from the wind, so as to prevent sudden desiccation. But experience
alone can determine wliat plants arc best suited for this, and to what extent the practice
can be can-icd. Nature gives tlie hint in the occasional luxuriance of plants accidentally
placed in favourable circumstances; man adopts it, and, improving upon it, produces
cabbages and turnips of enormous size; apples and pears of prodigious weight; and
cabbage-roses of four inclies in diameter; productions which may in some respects be
considered as diseased, as it were plethorically.
1131. To increase the numher, improve the quality, and increase the magnitude o f particular
parts o f vegetables, it is necessaiy to remove such parts of the vegetable as are not
wanted, such as the blooms of bulbous or tuberous rooted plants, when the under ground
part is to be increased, and the contraiy; the over-luxuriant wood-shoots and leaf-buds
of fruit-trees ; the fiower-stems of tobacco ; the male flowers and baiTon runners of the
cucumber tribe, &c. Hence the important operations of praning, ringing, cutting off
large roots, and other practices for improving fi-uits, and throwing trees into a bem-ing
state. A t first sight these practices do not appear to be copied from nature; but, iii-
dcpciidcntly of accidents by fire, already mentioned, whicli both prune and manure, ancl
of fniit-bcaring trees which, when partially torn up by the roots by high winds, or washed
out of the soil by ton-ents, always boar better afterwards, why may not the necessity that
man was nndcr, in a primitive state of society, of cutting or breaking off the branches of
trees, to form huts, fences, or fires, and the consequent vigorous shoots produced from
the parts where the amputation took place, or the larger frait on that part of the tree
whicli remained, have given the first idea of pruning, cutting off roots, &c. ? I t may bo
said that this is not nature, but art ; but man, though an improving animal, is still in a
state of nature, and all his practices, in every stage of civilisation, arc as natural to him
as those of the otlicr animals arc to them. Cottages and palaces arc as much natural
objects as the nests of birds, or the bun-ows of quadrupeds ; and all tlie laws and institutions
by which social man is guided in his morals and politics axe no more artificial
U U
than the mstinct which conp-cgatcs sheep and cattle in flocks and herds, and gnidcs them
in thoir choice of pasturage and shelter.
1132. To form new varieties o f vegetables, as well as of flowers and of useful plants
of every description, it is necessary to take advantage of the sexual differences, and to
operate in a manner analogous to crossing the breed in animals. Hence the origin of
new sorts of fmits. Even this practice is but an imitation of what takes place in nature
hy the agency of bees and other insects, .and the wind ; all the difference is, that man
operates with a particular end in view, and selects individuals possessing the particular
properties which ho wishes to perpetuate or improve. New viu-icties, or rather siibva-
notics, are formed by altering tho h.abits of plants ; hy dwarfing through want of
nonrishment ; variegating by aren.arious soils ; and in giving, or rather coiitiiiuiiig, peculiar
habits when fonned by nature, as in propagating from monstrosities—fasciculi of
shoots, weeping shoots, shoots with peculiar leaves, flowers, finit, &c.
1133. To propagate and preserve from degmeraaj approved varieties of vegetablc.s, it is
in general necessary to havo rccom-so to the different modes of propagating by extension.
Thus, choice apples and tree fniits arc prescived and multiplied by grafting ; othcix, as
the pine-apple, by cuttings or suckers ; choice carnations by layers, potatoes by cuttings
of the tubers, &c. But approved varieties of annuals are in general multiplied and preserved
by selecting seed from tho finest specimens, and paying particular attention to
supply suitable culture. This part of culture is the farthest removed from nature ; yet
there are, notwithstanding, examples of tlio fortuitous graft ; of accidental layers ; of
leaves (as of the Cardáminc pratéiisis), or detached portions, fonning natural cuttings,
dropping and taking root.
1134. T!k preservation o f vegetahks fo r fuiMre me is ciiectaH by destroying or rendering
donnant tho principle of life, and by warding off, as far as practicable, the progress
of chemical decomposition. Hcncc the herbs, or roots, or fruits of some vegetables, are
dried ; others arc placed beyond the reach of the active principles of vegetation, viz.
heat and moisture,—as seeds, cuttings, scions, roots, and fraits ; and some arc, in addition,
excluded from the air, or placed in very low temperatures. All these practices
aro obviously merely imitations of wlmt actually takes place in nature, from tho
withered grassy tussock to the hedgehog’s winter store ; and hence tho origin of Iicrb,
seed, frait, and root rooms and cellars, and packing plants and seeds for sending them
to a distance.
1135. The whole o f gardening, as an art o f culture, is hut a varied developement of the
above fundament.al practices, .all founded in nature, and for the most part rationally and
satisfactorily explained on chemical and physiological principles. Hence the great necessity
of tho study of botany to tho cultivator ; not iu the limited son.so in which the
term is often taken, as including mere nomenclature and classification, hut in that extended
signification of which we have endeavoured, iu this cliaptcr, to present a general
ontliuc. Thoso who would enter more minutely into tho subject wfll have recourse to
tho excellent works of Lindlcy, p.articul,arly to his Theory o f Horticulture, and to Do
C.andoUo’s Physiologie Végétale; but of all the works published on tho subject tho
Theory o f Horticulture is decidedly the best.
B O O K I I .
or THE STUDY OF TITE NATURAE AGENTS OP VEGETABLE GROWTII AND CULTURE.
1136. The composition and nature o f material bodies, and the laws o f their changes, foi-m
the next step in the study of the science of gardening. The earthy matters which
compose the surface of the globe, the air and light of the atmosphere, tlic water precipitated
from it, the heat and cold produced hy the alternation of day and night, and by
chemical composition and resolution, include all the elements concei-iicd iu vegetation.
We shall consider in succession Earths and Soils, Manures, aud tho Atmosjflicrc.
Chap. I.
O f Earths and Soils.
1137. Earths are derived from the rochs which arc exposed at the surface of the
globe, and soils are earths mixed ivith more or less o f the decomposed organised matter
afforded by dead plants and animals. Earths and soils, therefore, must he as vai'ious as
the rocks which produce them; and hcncc to understand then- nature and foi-matioii it is
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