CHAPTER XVI

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 a 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.

_The stem of the cutting is inserted one third or more 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. 160.--CUTTING-BOX.]

_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. 161.--VERBENA CUTTING READY FOR TRANSPLANTING.]

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. 162.--OLD GERANIUM PLANT CUT BACK TO MAKE IT THROW OUT SHOOTS FROM WHICH CUTTINGS CAN BE MADE.]

[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 =cion=; 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 cion and of the stock must come together_. Therefore the cion is set in the side of the stock. There are many ways of shaping the cion and of preparing the stock to receive it. These ways are dictated largely by the relative sizes of cion and stock, although many of them are matters of personal preference. The underlying principles are two: securing _close contact_ between the cambiums of cion 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 cion is firmly inserted. Fig. 165 shows the cion; Fig. 166, the cions 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 practiced in spring, as growth begins. The cions are cut previously, when perfectly dormant, and from the tree which it is desired to propagate._ The cions are kept in sand or moss in the cellar. Limbs of various sizes may be cleft-grafted,--from one half inch up to four inches in diameter; but a diameter of one to one and one 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 cions grow well, the entire top will be changed over to the new variety.

[Illustration: FIG. 165.--CION OF APPLE.]

[Illustration: FIG. 166.--THE CION 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 fiber). 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 practiced in spring with buds cut in winter. In ordinary summer budding (which is the usual mode) the “bud” or cion 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.

[Illustration: FIG. 168.--BUDDING. The “bud”; the opening to receive it; the bud tied.]

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 rosin; 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 color 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?