George William Johnson.

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For nearly twenty years the Author of these pages
has laboured to make the gardeners of England
more generally aware than they are, even at pre-
sent, of the principles on which their practices are,
or ought to be, founded. The results of his early
researches have, from time to time, been made
public, and those, together with more that are new,
he now offers to his readers in a collected and
orderly form.

He has thus laboured to impart the reasons for

horticultural practice, because it is certain that

gardening is no exception to the rule, that the

worst of ignorance is an ignorance of the reasons

for our conduct ; and if this volume aids in some

j degree to remove such ignorance from the gardener,

-^ the Author ^ill be happy in the consciousness that

^ he has helped the advance of plant- culture from

^ mere empiricism into the class of the rational

^ sciences.




Chapter I. — Sowing

Chapter II. — The Root

Chapter III. — The Stem and Branches

Chapter IV. — The Leaves

Chapter V,— The Sap . . .

Chapter YI. — The Flower

Chapter VIL — The Fruit and Seed .

Chapter VIII, — The Diaeases of Plants

Chapter IX. — Death and Decomposition







Gardening or Horticulture has for its objects, the
production of the fiTiits, flowers, and culinaiy vege-
tables of any climate, in any habitable place, in the
greatest perfection, and at the least possible expense.

Like all other human occupations, gardening is di-
visible into the science which teaches the principles
and circumstances on which the attainment of the de-
sired objects is founded ; and the art or practical skill
which enables the practitioner to secure those cir-
cumstances, and effectuate those principles.

It is to the first of these departments of knowledge
that the following pages are devoted: their prime
subject being the guidance afforded to the gardener
in the practice of his art by chemistry, vegetable
physiology, and other sciences.

If any one asks what those sciences have done for


gardening, I point to the discoveries of the late Mr.
Knight. The opinion of that most scienced horti-
cultuinst is also recorded in a letter from him now in
my possession, — the words should be engraved over
the portal of every garden : " Physiological know-
TICE IS LIKELY TO GIVE." Scicnce, it is time, can
never supersede the necessity for a practical ac-
quaintance with the operations of the spade, the
knife, and the hoe ; but it is their best guide, — a
pilot needed even by the most experienced, and let
it be remembered, that to botanists we owe nearly
the whole of our flowers, as well as our knowledge
of their habits; and that to information drawn
from their discoveries, we are indebted for the ma-
jority of oui' numerous varieties of fruits and culinary
vegetables, as well as for a laiowledge of their ana-
tomy and functions. Botany also affords the best
nomenclature for our plants ; and thus, to it we are
indebted for an enlightened practice, and a language
universally intelligible. But for another science,
chemistiy, the true nature of soils, of manures, of
the food and functions of plants, would be unknown
to us, and many of our simplest gai'den operations
would be inexplicable.

The gro\Ni:h of horticultural science has been slow;
for, although its dawn was in the Elizabethan age.


yet it never afforded any distinct light to gardening
until the beginning of the present centmy.

It is undoubtedly tme. that in much earher ages
there were suiinises bom of inquiiing minds, that
are startlingly in accordance with the results afforded
by modern vegetable chemistiy and physiology ; but
they were no more than sm'mises ; fortunate guesses
that, among many totally erroneous, happened to sa-
vour of ti-uth. Thus Pythagoras forbade the use of
beans as food, because he thought that they and human
flesh were created from the same substances, and
modern research has rendered it certain that that
pulse has among its constituents more animo-vege-
table matter than most other seeds. Empedocles
maintained that plants are sexual ; that they possess
life and sensation ; and that he remembered when
he was a plant himself, previously to being Empe-

Theophrastus and Pliny wrote more voluminously
upon plants, but not ^vith more knowledge of their
physiolog}^ ; and little or no improved progress is
really visible until the sixteenth centurj^ was well
advanced; for this branch of science was no bright
exception from the darkness enveloping all human
knowledge dming the middle ages, and it was not
until that period in which Bacon lived, that the
human mind threw off the trammels of the school-
men, and instead of arguing as to what must be,

B '2


proceeded to examine and search out what is. The
Reformation, the spirit of the age, was then not con-
fined to rehgion. By dehvering the human mind
from thraldom, and teaching man to search all things,
hut to retain only that which is good because true,
it gave an impetus to improvement which no tyrant
opposition has ever since been enabled to check.

Such men as Bacon, Peiresc, Evelyn, Grew and
Malpighi arose. Bacon was the first to teach aloud
that man can discover truth in no way but by observ-
ino- and imitating the operations of natm'e ; that
truth is born of fact, not of speculation ; and that
systems of Imowledge are to be founded not upon
ancient authority, not upon metaphysical theories,
but upon experiments and obsen-ations in the world
around us.

Peiresc was a munificent man of letters, whose
house, whose advice, and whose purse were opened
to the students of eveiy art and science. His library
was stored with the literature of every age, and his
garden with exotics from exerj clime, from whence
he delighted to spread them over Em'ope^.

Grew in England, and Malpighi in Italy, de-
voted themselves to the anatomical examination of
plants, and these were followed by Linnaeus, Gaertner,
and others, who, trusting only to the dissecting knife
and the microscope, soon precipitated into mins all
* History of English Gardening.


the fanciful fabrics of the Aristotelians. They were
the founders of that science of vegetable physiology,
which, enlarged and carried into practice by the
late Mr. Knight and others, has advanced horti-
culture to a degree of improvement, undreamed of
by their immediate predecessor, Heresbach, when
he informed the world that, if the powder of rams'
horns is sown, and well watered, " it will come to be
good aspai'agus."

The researches of Hales upon the circulatory
power of the sap-vessels, of Bonnet upon the func-
tions of the leaves, and of Du Hamel, Priestley,
Ingenhousz, Sennebier, Saussure, and others, upon
the action of hght, and the nature of the gases de-
veloped during the respiration of plants, imparted
still more useful knowledge to the gardener, and
rendered his art still less empirical.

The same philosophers directed their attention
also to the food of plants imbibed by their roots,
and to the examination of their various secretions ;
but here they were joined by another band of na-
ture's students, and no one conversant with the phi-
losophy of plant-culture but will remember the debt
he owes to Vauquelin, Lavoisier, Johns, Da^y, Liebig,
Lindley, Johnston, and Low.

It has been my endeavour to concentrate and arrange
the results of the researches of the above-named disci-
ples of nature in the following pages, — adding such rays,


derived from lesser lights, as aid to render the whole
more luminous, and such links of experiments and
obsen'ations from similar sources as make the work
more connected than it w^ould be without their aid.

In the arrangement of this work I might have fol-
lowed the more obvious plan of commencing with a
description of the seed, and the promotion of its pro-
duction ; but I found that the order adopted enabled
me to pursue more readily, and more progressively,
the phenomena and practices to be explained and

A few gardeners may still exist who venture to
think science useless — as there once existed a de-
votee of fashion who wondered w4iy it was not alwaj^s
candle-light ; but the great majority of gardeners
are now men of science, endeavouring thoroughly
to understand the reason of eveiy practice, and the
supposed cause of each effect. To those differing
from them I might name, if it would not be invi-
dious, nearly all the most successful of our modern
gardeners. To a man, these are w^ell acquainted with
gardening's relative sciences. I forbear from men-
tioning names, but I may remind my readers, with-
out fearing to offend, of two departed savans, M.
Lavoisier, and our fellow^-countrjmian, Mr. Knight.
Lavoisier, the Linnaeus of chemistiy, cultivated his
grounds in La Vendee on scientific principles, and
in a few years their annual produce doubled that from


equal spaces of his' neighbours' soil. Mr. Knight has
scai'cely left a department of our horticulture unim-
proved, by that combination of scientific ^vith prac-
tical knowledge which he, perhaps more than anv
other man, had united in his own mind.

It behoves every gardener to follow in theu" steps,
for though the great men who have gone before
have done much for gardening, yet still more remains
to be accomplished. We still, on most points, do
and must ever see through a glass dai'kly ; but that
is no reason why any one should refrain from the
efifort to elicit a ray towards diminishing the obscu-
rity — and we may all, without fear of misspending our
laboui', continue to act as if botany could still fur-
nish something new, and as if chemistry and phy-
siology had still some secret to reveal to the en-



That the seed should have a perfectly developed em-
bryo, and have arrived to nearly perfect ripeness, is
essential to its being able to germinate. The rea-
son for this is obvious : the young plant requires for
its earliest nourishment a peculiar compoimd, usually
saccharine matter ; and this compoimd, in accordance
with that universal fitness of things which demon-
strates the wisdom of God, is always generated by
the combined agency of heat, moistm'e, and oxygen
gas, from the substances most abmidant in the fully
ripened seed. Let barley be the example. Saccha-
rine matter is essential for the first nourishment of
the radicle and plumule,^ and into such saccharine
matter is starch converted, by the combined agency I
have named. It is starch, therefore, that is the chief
constituent of the seed. But if barley be gathered
immature, and dried, the chief ingredient is mu-
cilage or gum ; and this, if exposed to the essentials
for germination, heat, moisture and oxygen gas, in-

^ The thread-like sprouts, becoming afterwards the root and
stem, are so named.


Stead of passing into saccharine matter, is converted
into acetic acid.

As it is imperative that eveiy seed should have
nearly attained to ripeness before it acquii'es the power
of germinating, and that the more perfect the ripeness
the more perfect and the more healthy that germina-
tion, so is it equally ceitain, that the length of time it
retains the power of germination differs in almost every
plant. The seed of the coffee shrub loses all vege-
tative power, unless sown within a few weeks after it
has been gathered, whilst that of the melon improves
by being stored for one or two years, and celery re-
mains capable of germinating for five times the last-
named period ^. These and all other instances within
my knowledge demonstrate, that the more starchy
and other matters into which nitrogen^ does not enter
as a constituent, which a seed contains, the longer v61\
it retain vitality ; and two familiar instances are com-
mon rice and the kidney bean. Eice contains 85 per
cent, of starch, and will retain its vegetative powers
for many years ; whilst kidney beans, which contain

* Melon seeds^ by keeping, improve only in the sense in which
gardeners consider the plant improved, viz. less of stem is produced,
and the fruit is matured earlier. Whatever checks the develop-
ment of the early organs, the radicle and plumule, produces this
effect, and this is effected by age in the melon seed ; its starchy
component diminishes in quantity, being gradually converted into
albumen. This is less easily transmuted to the soluble matters
necessary for the nourishment of the parts first developed.

^ Nitrogen, a gas present in most animal matters.


one-third their weight of animo-vegetable matter and
other constituents, of which nitrogen is a component,
will not vegetate healthily a second season.

Carolina, Rice.

Water 5.00

Starch 85.07

Parenchyma 4.80

Gluten 3.60

Uncrystallizable sugar . . . 0.29
Grummy matter, approaching

starch 0.71

Oil 0.13

Phosphate of lime . . . . 0.13

Kidney Beans.

Skins 288

Starchy fibrous matter . . . 425

Starch 1380

Animo-vegetable matter . . . 799

Extractive 131

Albumen and vegeto-animal mat-
ter 52

Mucilage 744

Loss SI

3840 b

* M. Braconnot, in Ann. de Chym. iv. 370.
'' Einhof in Gehlen's Journ. vi. 545.

CH. I.] SOWING. ' 11

This speedy loss of \-itality in seeds abounding in
nitrogenous matter, is just what the chemist would
predict ; for all bodies so constituted are most prone
to decomposition and decay.

The following list, furnished by the late Mr. Lou-
don, shows the greatest age at which some of our
common garden seeds germinate freely ; and this
result of experience is quite concuiTent ^vith our
knowledge of their chemical constitution : —

One year. Peas, beans, kidney beans, carrot, par-
snip, oraches, herb-patience, rhubarb, elm, poplar,
and willow.

Tivo years. Radish, salsafy, scorzonera, purslane,
the alUums, cardoon, rampion, alisander, love apple,
capsicum, egg-plant.

Three years. Sea-kale, artichoke, lettuce, mari-
gold, rue, rosemaiy.

Four years. Brassicas, skirret, spinach, asparagus,
endive, mustard, tarragon, borage.

Five and six years. Burnet, sorrel, parsley, dill,
fennel, chervil, hyssop.

Ten years. Beet, celery, pompion, cucumber, melon.

Now in this list generally, as already observed,
those with the most of nitrogenous matters among
their component parts, are the first to decompose,
and consequently lose their \-itahty ; and those with
the greatest amount of starch and lignin, or more
carbonaceous constituents, retain their germinating


power the longest, and for the evident reason, that
such ai'e less prone to decay.

At the same time, let me guard myself from being
misconceived to say, that such are the only chemical
causes for a seed's curtailed or protracted vitality.
On the contrary, I am "well awai'e there are others,
and for example may be taken many seeds abounding
with expressed oil. These, exposed to the free ope-
ration of the air, gradually lose their \'itality, as the
oil they contain becomes rancid. Presented from the
action of the air, no seeds are more retentive of vi-
tality, apparently because when so preserved, the oil
they contain will remain sweet and unchanged for
ages. This is the reason that in earth excavated
from great depths below the sui-face, charlock, mus-
tard, and such like plants, ha\ing oleaginous seeds,
are found to have retained their embiyo ^^tality.

In considering this subject, let it ever be kept in
mind, that almost every species of seed has a peculiar
degree of heat, and a peculiar amoimt of moisture,
at or approaching to which its vitality will be excited
into action. Therefore, in all obsei'vations on the
life-retaining power of seeds, and in conclusions
deduced from experiment, it must be carefully
secured that they have not been excited to those
initiatory steps of germination, which being taken and
then checked, invariably cause the destruction of a
seed's vital powers.

CH. I.] SOWING. 13

This brings me to the consideration of the con-
tingencies necessaiy to cause a seed's germination.

A certain degi'ee of warmth is essential, for no
known plant has seeds that will genninate below or
at the freezing point of water. A temperature above
32° of Fahrenheit's thermometer, therefore, is
requisite ; and the plants whose seeds will germinate
nearest to that low degree of temperature, in this
country, are the winter weeds. For example, I have
found the seeds of the Poa annua, the commonest
grass of our gravel walks, germinate at SS"^, and the
seeds of groundsel (Senecio vulgaris) would probably
requii'e no higher temperature. But, on the other
hand, the temperature must not be excessively high.
Even no tropical seed, probably, will germinate at a
temperature much above 120^ F., and we know from ' tl^^f.i ix^
the experiments of MM. Edwards and Colin, that ' ^

neither wheat, oats, nor barley will vegetate in a
temperature of 113°.^

Every seed differing in its degree of excitability,
consequently has a temperature without which it
will not vegetate, and from which cause arise the
consequences that different plants require to be so"uti
at different seasons, and that they genninate with
various degrees of rapidity.

For example, two vaiieties of early pea, sown on a
south border on the same day, and treated strictly

^ Jour, de Pharmacie, xxii. 210.



[CH. I.

alike throughout their growth, were about a fortnight
differing in all their stages of vegetation.

Sown In bloom Gathered from

Cormack's Prince

Albert . . Jan. 4. April 1. May 14-

Warwick . Jan. 4. April 13. May -28.

Adanson found that, under the most favourable
circumstances, various garden seeds might be made
to germinate in the following veiy different spaxies of

Spinach, Beans, Mustard . 3 days.

Lettuce, Aniseed .... 4

Melon, Cucumber, Cress . 5

Eadish, Beet 6

Orache 8

Purslain 9

Cabbage 10

Hyssop 30

Parsley 40 or 50 do.

Almond, Chesnut, Peach . 1 year.

Rose, Hawthorn, Filbert . 2 do.^

In one instance M. Adanson certainly must have
experimented with old seed, for I have fomid good
new parsley seed, sown on fresh fertile soil in May,
had germinated in two days, and its leaves were
above the surface within a week from the day of
" Families des Plantes, i. 85.

CH. I.] SOWING. 15

sowing. Then again in the case of rose seed, — at all
events, in the case of that of the dog rose, — if the hips
he allowed to endure the frosts of winter before they
are gathered, their seed vail geiToinate in much less
time than is named by M. Adanson. This lesson
was probably taught the gardener by nature, for the
hips of roses never shed their seed in this country
until they have been frosted.

The gardener should always bear in mind, that it
would be a very erroneous conclusion, because a seed
does not geiTuinate at the accustomed time, that
therefore its vegetating powers ai'e departed. No
two seeds taken from the same seed-vessel ger-
minate precisely at the same time ; but, on the
contrary, one will often do so promptly, while its
companion seed will remain dormant imtil anotlier
year. M. De Candolle relates an instance where
fresh tobacco seedhngs continued to appear annually
for ten years on the same plot, though no seed was
sown after the first sowing ; and the same phenomenon
usually occurs for two or three years, when the seed
of either the peony or hawthorn are sown. Why
one seed is more easily excited than another is as
yet unexplained, but the wisdom of this one of many
pro-visions for avoiding the accidental extinction of a
species in any given locality is readily discerned.
An ungenial spring may destroy the plants from
those seeds which first germinated, but this could


scarcely occur also to those of the second and third
year, or even to those which were only a few weeks
later in their vegetation.

It is not possible to enunciate a general rule

I relative to germinating temperatures requiring no
exceptions, but in general, for the seeds of plants
natives of temperate latitudes, the best germinating
temperatiu'e is about 60° ; ^ for those of half-hardy
plants 70° ; and for those of tropical plants about
SO'^; and the necessity for such temperatui'es
depends upon the same causes that prevent the
incubation of eggs unless they be kept for a certain
period at a temperatui'e of about 100^. The
requisite changes are not produced either in the seed
or in the egg, miless it be submitted to the pro-
pitious temperature — but why this is requisite to
develope the forms, and effect the changes, without

' wliich there is no vitality, is a secret at present
witlilield from man s understanding by the Almighty

I architect, and w^e must rest satisfied with the
approximate Imowledge that heat is the vast and all
pen^ading agent he employs to call life into existence.
Although temperatm'es ranging between 60° and
80"^, are those most usually propitious to germina-
tion, yet a much higher temperature can be endured
by seed without its vitality being destroyed, and

* Except where otherwise stated, Fahrenheit's thermometer is
referred to in the temperatures particularized.

CH. I.] SOWING. 17

indeed may be employed Avith great advantage,
when the seed from age or other cause geinninates
A\-ith difficulty. Dr. Lindley foimd the seeds of a
raspberr}^ germinate, though they must have endured
a temperature of 230'^ in the boiling synip of the
jam, -whence they were taken ; and other instances
are known where peas submitted to a temperature
of 200°, and, left in the water for twenty-four
hours until cool, germinated more readily than
other peas not so treated. The seeds of Acacia
lophantha also produced seedlings after being boiled
in water for five minutes. The effects produced by
this high temperature, are to permanently soften the
cuticle of the seed, and render it more readily per-
meable by the air ; also aiding the conversion of the
starchy components of the seed into saccharine
matter ; but if the boiling be contmued until the com-
position of the germen is altered, the germinating
power of the seed is destroyed.

These facts lead to the verj- important inquiry,
whether the soil has any influence over the tempera-
ture occurring to the seed, and to the roots of plants
placed beneath its surface. The researches of M.
Schluber answer this query in the affirmative. This
distinguished German chemist fomid that when the
temperature of the upper sui'face of tlie earth was 77°
in the shade, various soils, exposed to the sun from



eleven to three, in vessels four inches square and
half an inch deep, attained the temperatures shewn
in this table.

Wet. Dry.

Siliceous Sand, bright yellowish gray 99.1 11 '2. 6

Calcareous Sand, whitish gray . . 99.3 112.1

Gypsum, bright w^liite gray . . . 97.3 110.5

Sandy Clay, yellowish 98.2 111.4

Loamy Clay, yellowish . . . , 99.1 112.1
Stiff Clay, or Brick Earth, yellowish

gray 99.3 112.3

Fine bluish gray Clay 99.5 113.0

Lime, white 96.1 109.4

Magnesia, pure wiiite 95.2 108.6

Garden Mould, blackish gray . . 99.5 113.5

Arable Soil, gray ...... 97.7 111.7

Slaty Marl, brownish red .... 101.8 115.3

The results of M. Schluber's experiments demon-
strate that which our knowledge of the laws of caloric
would have induced us to pre-suppose, namely, that
light coloured earths by reason of their reiiecting
most rays of heat, are warmed much more tardily
than dark coloured earths. It was this conclusion
which induced me, some years now past, to try the
effect of sprinkling coal ashes over rows of autumn
sown peas. The peas invariably appeared above

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Online LibraryGeorge William JohnsonThe principles of practical gardening → online text (page 1 of 20)