Propagation By Cuttings For House Plants
( Originally Published 1923 )
It is easy, indeed, to grow from seeds such plants as are described in the preceding chapter; but this is impossible with the named varieties of fuchsias, geraniums, and such like. Then, again, seeds of such things as rubber plant and screw pine are seldom offered for sale. There-fore, one must resort to some other means of propagation.
Cuttings or slips, made from pieces of the stem or root or leaf, are generally used. Sometimes, however, increase is by some form of division of the roots; each plant has its own particular method. But most of the plants which may be grown easily in the house, and which are not grown from seed, may be grown from cuttings of the stem.
THE SAND BED
The best medium in which to root cuttings is damp sand. An ordinary soap box, cut down so as to be about six inches deep, will furnish sufficient space to root all the cuttings necessary to supply any ordinary window garden. In the bottom bore five or six one-inch holes, and put a layer about an inch deep Of broken pots, gravel, or broken up coal clinkers for drainage. Over this put a little sphagnum moss to keep the sand from sifting down through the drainage; then put in a three or four inch layer of sand; moisten and pack it down with a brick. Have it perfectly level. The bed is now ready for the cuttings.
One drawback tO the home propagation of plants is the great fluctuation of temperature. If enough bottom heat can be given so that the temperature of the sand can be kept about 8o degrees day and night and the box deep enough so that a piece of glass or newspaper can be placed over the top without injuring the cuttings, the difficulty can be got around.
HOME-MADE PROPAGATING BOX
One amateur solved the problem in a very simple and inexpensive way. This is how he did it:
"Three boxes are necessary. Soap boxes will do, if the length and width are equal, so that they will closely fit upon one another. Besides these, there will be needed a large, deep pan; two half-gallon jugs; sufficient zinc to serve as a bottom for one of the boxes; one peck of coarse sand, and a foot heater, such as is used in carriages during the winter.
"Using one of the boxes as a base, bore a few holes near the top for ventilators, which can be controlled by the use of corks. In this lower box place jugs filled with hot water during the day, when little heat will be required. At night use the foot heater, putting in about one-half cake of fuel just before retiring. Take off the top of one of the boxes and nail strips along the sides wide enough to hold the pan of water. This box will rest over the compartment with the heater. Cut the last box so that the back is about three inches higher than the front, in order to get the best distribution of light. Fill it to the depth of three inches with coarse sand.
"This is the upper box, and should be covered with a pane Of glass. If these boxes fit tightly upon one another so no heat can escape, and if the jugs and pan are filled with hot water, a temperature of 8o degrees can be maintained all day by filling the jugs two or three times. Keep a small thermometer plunged in the sand, and for a few days before putting in your cuttings experiment to ascertain under just what conditions the heater will do the most satisfactory work.
" I filled the box with cuttings from rubber plants, plunging them in the sand without other preparation than cutting them with a sharp knife, leaving the surface clean and smooth. I did not lose one of the lot. Rubber plants grow so tall after a few years that one feels impelled to shorten them. This can easily be accomplished by cutting off the top and rooting it. Young plants may also be started from each joint of the old stem, thus from one old plant which has outgrown its usefulness a great many can be raised easily. After the rubber plants I put in Pandanus Veitchii with success. Then I took a few large leaves of Begonia Rex, cut the ribs on the back, made a number of incisions in the leaves, and then placed them on the sand, pressing them down to make a good contact all around. From each incision a plant started, and in six weeks I potted off twenty-five sturdy, clean begonias from five leaves.
"During the day I kept my bed in a good light near the window, ventilated it by raising the glass, protected it with paper when the sun was strong, and at night, when cold, I threw a carriage robe over it. From the results I have had I feel convinced that the little propagating bed is as practical as the larger ones used in greenhouses, and will do the same work on a reduced scale."
Before putting the cuttings in the cutting bed the amateur should run it a day or two in order to learn how to maintain an even heat.
HOW TO MAKE A CUTTING
All cuttings of the stems are made nearly alike, the only difference being that with different kinds of plants the length of the cuttings varies in proportion to the diameter of the stem and the distance between the buds. For instance: a geranium cutting is usually made about three or three and one half inches long, while that of a heliotrope is usually one and a quarter to one and a half inches long.
A sharp knife is needed so as not to bruise the stem. To make a good geranium cutting select a well-ripened end of a stem, cut it off at the required length, and just below a node (where a leaf is attached). It is important that the cut should be made just below a node, for roots are more freely produced than when the cut is made between the nodes. In many instances cuttings will not root at all if the cut is made anywhere but directly under the node.
Trim off carefully all the leaves except one at the top and trim off also all the stipules, those leafy growths on the stems where the leaves join. If these are left on they will decay and may lead to the cutting rotting, too.
Put the cutting in the sand, setting it deep enough to hold it erect, which will be about three-quarters of an inch. If you are making a lot of cuttings quite a number can be made before putting them in the sand; but do not let the cut surface be exposed to the air too long or the chances of rooting will be greatly lessened.
Geranium cuttings should be set about an inch apart in the row, and the rows about two inches apart. If they are put closer they are much more likely to rot. Always dibble in the cuttings; simply forcing them down into the sand will injure the ends so that the cuttings will not root. After putting the cuttings in the sand, water them and shade them from the sun with a single sheet of newspaper. Other plants which may be propagated this way are heliotrope, ageratum, coleus, abutilon, hydrangea, etc.
The dracana is another plant which may be cultivated by cuttings of the stems, but instead of making these cuttings as I have described for the geranium, the long, bare stem is cut into pieces two or three inches long, each of which must have a node, and the pieces laid down in the sand — they should be just covered. Each piece will make at least one new plant. When the new growth is 2i to 3 inches long, it is taken off the old stem and put in the cutting bench just like any cutting of the stem. The old stem is left in the sand for it frequently will provide more cuttings.
The bouvardia (one of the best plants one can grow for cut flowers at Christmas time) is increased in much the same way, but instead of cutting the stem into small pieces the root is cut up and the pieces treated exactly as if they were seeds.
PROPAGATING BY LEAVES
That new plants can be made from the leaves of old plants is a never failing source of interest to a great many people. The plant which is most commonly propagated this way is Begonia Rex. Take an old leaf and turn it upside down on a board, and with a sharp knife cut the veins. Then place the leaf right side up on damp sand, pin it down with toothpicks which have been bent in two, and shade it. At each cut in 'the leaf's vein a new plant will be formed. As soon as they have made a couple of small leaves separate the young plants from the old leaf and pot them off in a sandy soil with lots of leafmould in it.
The pretty little marble-leaved peperomia is another plant propagated from the leaf, but instead of cutting the leaf it is laid on the sand and the leaf stalk covered up. The gloxinia may also be propagated by tubers forming at the cuts.
The umbrella plant (Cyperus alternifolius) is perhaps the easiest of all plants to ' propagate by rooting the leaves. It is the simplest anyway. Cut off the bunch of leaves with, perhaps, one-quarter or one-eighth of an inch of stem, and put it in water. Never allow the water to become stale, which is best done by adding to it a few pieces of charcoal. In a few weeks a new plant will be seen pushing up from among the leaflets. Carefully separate it from the old leaf and pot it up.
PROPAGATING BY OFFSET
Some plants produce a lot of suckers or rosettes at the base of the plant, near the ground. Familiar examples of this are hen and chickens, and the screw pine (Pandanus Veitchi:). The former forms little rosettes which simply have to be taken off and put in sand for a short time. The suckers from the screw pine are taken off, the leaves shortened back to reduce transpiration, and then put in the sand like cuttings of other plants. They root in a few weeks.
PRoPAGATING BY RUNNERS
Runners differ from offsets in that the plant produces a small wiry stem which will form a new plant if the end is covered with soil. The two commonest house plants increased by this method are the strawberry geranium and the sword fern. The straw-berry geranium will form new leaves on these runners before roots are produced, so if there is not a chance to allow them to root in the pot before separating the young plantlets from the mother plant they may be taken off and put in sand like any ordinary cutting. The young ferns must be rooted before being separated from the parent plants.
MAKING NEW RUBBER PLANTS
A well-kept rubber plant will in a couple of years become too ungainly for the house. Many times one does not care to part with it because of some sentiment attached to it. Two things may be done to make a shapely plant. The quickest way to reduce the plant is to cut it down to within a foot or fifteen inches of the ground. New shoots will appear in a short time that will trans-form the stub into a shapely, round-headed tree.
The other thing to do is to make a slanting cut in the stem far enough from the top so that when cut off it will make a shapely plant. Put a small piece of wood or char-coal in the cut to keep it open. Over the cut lay some damp sphagnum moss, and be sure that it always is damp, but do not let it become too damp or it may get sour. In a few weeks new roots will be seen protruding through the moss. When a mass of roots has been produced cut the stem off below the moss and pot the plant, moss and all, in a good potting soil. Put it in a shaded place for a few days until the roots have taken hold of the soil.
This method is often varied by carefully splitting a pot in halves, putting them about the stem of the plant, and then filling the pot with a mixture of soil and sphagnum moss. The moss is added to prevent rapid drying out of the soil.
Any plant which will grow from cuttings may be increased by this method, but it is usually employed only on hardwooded plants like the rubber plant, ardisia, dracena, etc.