BUD PROPAGATION
We have learned (in Chap. VI) that plants propagate by means of
seeds. _They also propagate by means of bud parts,—as rootstocks
(rhizomes), roots, runners, layers, bulbs._ The pupil should
determine how any plant in which he is interested naturally
propagates itself (or spreads its kind). Determine this for
raspberry, blackberry, strawberry, June-grass or other grass,
nut-grass, water-lily, May apple or mandrake, burdock, Irish potato,
sweet potato, buckwheat, cotton, pea, corn, sugar-cane, wheat, rice.
Plants may be _artificially propagated_ by similar means, as by
_layers_, _cuttings_, and _grafts_. The last two we may discuss here.
=Cuttings in General.=—_A bit of a plant stuck into the ground stands
a chance of growing; and this bit is a_ =cutting=. Plants have
preferences, however, as to the kind of bit which shall be used,
but _there is no way of telling what this preference is except by
trying_. In some instances this preference has not been discovered,
and we say that the plant cannot be propagated by cuttings.
Most plants prefer that the cutting be made of the =soft= or =growing
parts= (called “wood” by gardeners), of which the “slips” of geranium
and coleus are examples. Others grow equally well from cuttings
of the =hard= or =mature parts= or =wood=, as currant and grape;
and in some instances this mature wood may be of roots, as in the
blackberry. In some cases cuttings are made of tubers, as in the
Irish potato (Fig. 60). Pupils should make cuttings now and then. If
they can do nothing more, they can make cuttings of potato, as the
farmer does; and they can plant them in a box in the window.
[Illustration: FIG. 158.—GERANIUM CUTTING.]
[Illustration: FIG. 159.—ROSE CUTTING.]
=The Softwood Cutting.=—The softwood cutting is made from tissue that
is still growing, or at least from that which is not dormant. _It
comprises one or two joints, with a leaf attached_ (Figs. 158, 159).
It must not be allowed to wilt. Therefore, it must be _protected from
direct sunlight and dry air until it is well established; and if it
has many leaves, some of them should be removed, or at least cut in
two, in order to reduce the evaporating surface._ The soil should be
uniformly moist. The pictures show the depth to which the cuttings
are planted.
For most plants, the proper age or maturity of wood for the making
of cuttings may be determined by giving the _twig a quick bend: if
it snaps and hangs by the bark, it is in proper condition; if it
bends without breaking, it is too young and soft or too old; if it
splinters, it is too old and woody_. The tips of strong upright
shoots usually make the best cuttings. Preferably, each cutting
should have a joint or node near its base; and if the internodes are
very short it may comprise two or three joints.
[Illustration: FIG. 160.—CUTTING-BOX.]
_The stem of the cutting is inserted one third or more of its length
in clean sand or gravel, and the earth is pressed firmly about it._
A newspaper may be laid over the bed to exclude the light—if the sun
strikes it—and to prevent too rapid evaporation. The soil should be
moist clear through, not on top only.
[Illustration: FIG. 161.—VERBENA CUTTING READY FOR TRANSPLANTING.]
_Loose sandy or gravelly soil is used._ Sand used by masons is good
material in which to start most cuttings; or fine gravel—sifted
of most of its earthy matter—may be used. Soils are avoided which
contain much decaying organic matter, for these soils are breeding
places of fungi, which attack the soft cutting and cause it to “damp
off,” or to die at or near the surface of the ground. If the cuttings
are to be grown in a window, put three or four inches of the earth
in a shallow box or a pan. A soap box cut in two lengthwise, so that
it makes a box four or five inches deep—as a gardener’s flat—is
excellent (Fig. 160). Cuttings of common plants, as geranium, coleus,
fuchsia, carnation, are kept at a living-room temperature. As long as
the cuttings look bright and green, they are in good condition. It
may be a month before roots form. When roots have formed, the plants
begin to make new leaves at the tip. Then they may be transplanted
into other boxes or into pots. The verbena in Fig. 161 is just ready
for transplanting.
[Illustration: FIG. 162.—OLD GERANIUM PLANT CUT BACK TO MAKE IT THROW
OUT SHOOTS FROM WHICH CUTTINGS CAN BE MADE.]
It is not always easy to find growing shoots from which to make the
cuttings. The best practice, in that case, is _to cut back an old
plant, then keep it warm and well watered, and thereby force it to
throw out new shoots_. The old geranium plant from the window garden,
or the one taken up from the lawn bed, may be treated this way (see
Fig. 162). The best plants of geranium and coleus and most window
plants are those which are not more than one year old. _The geranium
and fuchsia cuttings which are made in January, February, or March
will give compact blooming plants for the next winter; and thereafter
new ones should take their places_ (Fig. 163).
[Illustration: FIG. 163.—EARLY WINTER GERANIUM, from a spring
cutting.]
=The Hardwood Cutting.=—_Best results with cuttings of mature wood
are secured when the cuttings are made in the fall and then buried
until spring in sand in the cellar._ These cuttings are usually six
to ten inches long. They are not idle while they rest. The lower end
calluses or heals, and the roots form more readily when the cutting
is planted in the spring. But if the proper season has passed, take
cuttings at any time in winter, plant them in a deep box in the
window, and watch. They will need no shading or special care. Grape,
currant, gooseberry, willow, and poplar readily take root from the
hardwood. Fig. 164 shows a currant cutting. It has only one bud above
the ground.
[Illustration: FIG. 164.—CURRANT CUTTING.]
=The Graft.=—_When the cutting is inserted in a plant rather than in
the soil, it is a graft_; and the graft may grow. In this case the
cutting grows fast to the other plant, and the two become one. When
the cutting is inserted in a plant, it is no longer called a cutting
but a =scion=; and the plant in which it is inserted is called the
=stock=. Fruit trees are grafted _in order that a certain variety or
kind may be perpetuated_, as a Baldwin or Ben Davis variety of apple,
Seckel or Bartlett pear, Navel or St. Michael orange.
_Plants have preferences as to the stocks on which they will
grow; but we can find out what their choice is only by making the
experiment._ The pear grows well on the quince, but the quince does
not thrive on the pear. The pear grows on some of the hawthorns, but
it is an unwilling subject on the apple. Tomato plants will grow on
potato plants and potato plants on tomato plants. When the potato
is the root, both tomatoes and potatoes may be produced, although
the crop will be very small; when the tomato is the root, neither
potatoes nor tomatoes will be produced. Chestnut will grow on some
kinds of oak. In general, one species or kind is grafted on the same
species, as apple on apple, pear on pear, orange on orange.
_The forming, growing tissue of the stem_ (on the plants we have
been discussing) _is the_ =cambium= (Chap. X), _lying on the outside
of the woody cylinder beneath the bark_. In order that union may
take place, _the cambium of the scion and of the stock must come
together_. Therefore the scion is set in the side of the stock. There
are many ways of shaping the scion and of preparing the stock to
receive it. These ways are dictated largely by the relative sizes
of scion and stock, although many of them are matters of personal
preference. The underlying principles are two: securing _close
contact_ between the cambiums of scion and stock; _covering the
wounded surfaces_ to prevent evaporation and to protect the parts
from disease.
On large stocks the commonest form of grafting is the =cleft-graft=.
The stock is cut off and split; and in one or both sides a
wedge-shaped scion is firmly inserted. Fig. 165 shows the scion; Fig.
166, the scions set in the stock; Fig. 167, the stock waxed. It will
be seen that the lower bud—that lying in the wedge—is covered by the
wax; but being nearest the food supply and least exposed to weather,
it is the most likely to grow: it will push through the wax.
=Cleft-grafting= _is practised in spring, as growth begins. The
scions are cut previously, when perfectly dormant, and from the
tree which it is desired to propagate_. The scions are kept
in sand or moss in the cellar. Limbs of various sizes may be
cleft-grafted,—from a half inch up to four inches in diameter; but a
diameter of one to one and a half inches is the most convenient size.
All the leading or main branches of a tree top may be grafted. If the
remaining parts of the top are gradually cut away and the scions grow
well, the entire top will be changed over to the new variety.
[Illustration: FIG. 165.—SCION OF APPLE.]
[Illustration: FIG. 166.—THE SCION INSERTED.]
[Illustration: FIG. 167.—THE PARTS WAXED.]
Another form of grafting is known as =budding=. In this case a single
bud is used, and it is slipped underneath the bark of the stock and
securely tied (not waxed) with soft material, as bass bark, corn
shuck, yarn, or raffia (the last a commercial palm fibre). Budding is
performed _when the bark of the stock will slip or peel_ (so that the
bud can be inserted), and _when the bud is mature enough to grow_.
Usually budding is performed in late summer or early fall, when the
winter buds are well formed; or it may be practised in spring with
buds cut in winter. In ordinary summer budding (which is the usual
mode) the “bud” or scion forms a union with the stock, and then lies
dormant till the following spring, as if it were still on its own
twig. Budding is mostly restricted to young trees in the nursery.
In the spring following the budding, the stock is cut off just above
the bud, so that only the shoot from the bud grows to make the future
tree. This prevailing form of budding (shield-budding) is shown in
Fig. 168.
SUGGESTIONS.—=128.= Name the plants that the gardener propagates
by means of cuttings. =129.= By means of grafts. =130.= The
cutting-box may be set in the window. If the box does not receive
direct sunlight, it may be covered with a pane of glass to prevent
evaporation. Take care that the air is not kept too close, else
the damping-off fungi may attack the cuttings, and they will rot
at the surface of the ground. See that the pane is raised a little
at one end to afford ventilation; and if the water collects in
drops on the under side of the glass, remove the pane for a time.
=131.= Grafting wax is made of beeswax, resin, and tallow. A good
recipe is one part (as one pound) of rendered tallow, two parts
of beeswax, four parts of resin; melt together in a kettle; pour
the liquid into a pail or tub of water to solidify it; work with
the hands until it has the colour and “grain” of taffy candy, the
hands being greased when necessary. The wax will keep any length
of time. For the little grafting that any pupil would do, it is
better to buy the wax of a seedsman. =132.= Grafting is hardly to
be recommended as a general school diversion, as the making of
cuttings is; and the account of it in this chapter is inserted
chiefly to satisfy the general curiosity on the subject. =133.= In
Chap. V we had a definition of a plant generation: what is “one
generation” of a grafted fruit tree, as Le Conte pear, Baldwin, or
Ben Davis apple? =134.= The Elberta peach originated about 1880:
what is meant by “originated”? =135.= How is the grape propagated
so as to come true to name (explain what is meant by “coming
true”)? currant? strawberry? raspberry? blackberry? peach? pear?
orange? fig? plum? cherry? apple? chestnut? pecan?
[Illustration: FIG. 168.—BUDDING. The “bud”; the opening to receive
it; the bud tied.]