Vegetative Propagation of Houseplants: Fast and Effective

Vegetative Propagation of Houseplants: Fast and Effective

J. van Ingen Schenau

This is a term applied to the, propagation of plants from parts other than seeds or spores. Parts may consist of stems, leaves, or roots. In general, plants raised by vegetative propagation reproduce the parent plant exactly, although there are some rare exceptions to this rule. (A leaf cutting from a snake plant, the variety whose leaves are marked with yellow stripes, produces offspring completely green.) One advantage of vegetative propagation is that mature plants are produced faster. The method most used for houseplants is taking cuttings. A cutting can come from any part of a plant in active growth:

Tip cuttings, stem sections with eyes, leaf cuttings and root cuttings

Most tender plants can be propagated from 5 - 10 cm tips or portions of the stem with eyes. Place cuttings in water, damp vermiculite or perlite; bottom heat of 18 - 31°C aids rooting. Tropicals such as crotons and ficus root best at 24°C. It is recommended to use rooting powders (dip the base of the cuffing into powder or solution) to assist harder, slower-rooting cuttings in speedier rooting. This is hardly needed with quick-rooting cuttings (impatients, tradescantia). Certain waxy plants, like begonias, ivy, peperomia, do not need a glass cover. But soft cuttings of other plants such as coleus, gesneriads fuchias, gardenia, hibiscus, oleander, crotons, etc. give oft more water than they can take up, and it is most important that their leaves and stems are kept from wilting. A glass enclosure, or hood of plastic film for the first week or two prevents excessive dehydration, as it will maintain a high humidity. This cover may be removed after a cuffing "heals" its cut, forming callus and as the first roots being to show. Light is also a factor in the rooting of cuttings. While in the beginning it is necessary to shield the cuttings from bright sun, light intensify for most cuttings, except the shade lovers, should be as high as possible without causing the plant to wilt. In sun, cuttings continue to manufacture food without drawing on the stored supply and exhausting it.

From woody plants you can take hardwood cuttings 15 - 25 cm long, made from ripened cane of heat loving shrubs, such as roses, poinsettias, allamanda, bougainvillea, jasmine, etc. Insert two-thirds into damp vermiculite or peat with perlite to keep the woody stem moist. The use of a rooting powder for hardy wood is a must! A simple polyethylene bag over your cuttings makes an ideal greenhouse suitable for the rooting of cuttings that take as long at 6 to 10 weeks to form roots, such as azaleas, camellias and gardenias. Polyethylene film allows for the exchange of oxygen and carbon dioxide, without which roots do not develop properly.

Leaf cuttings offer the gardener a ready means for propagation of certain plants. The pickaback plant produces plantlets on the leaves, when growing in the wild. The outer leaves topple over the ground, where the plantlets on the leaves, take root and grow. In propagating them under artificial conditions, they can be cut oft with 2 cm leafstalks and inserted into individual flowerpots with standard mixture. Keep them shaded for a few weeks. Kalanchoe pinnata produces plantlets in the notches along the leaf margin. In nature these fall off and in a suitable environment they grow quickly. Leaf cuttings from African violets root easily in water or vermiculite, and give many plantlets. The original leaf can be replanted if you want more plants. Some tropical plants possessing leaves with fleshy veins are frequently propagated by leaf sections, consisting of a whole leaf or a piece of a leaf. Peperomias, and almost any of the subtropical species of sedum root ideally from whole leaves. Leaf sections can be taken from begonia (rex), gloxinia, hoya, streptocarpus. A leaf section of these plants develops young plants from the prominent primary vein, if the artery or rib is cut. Mature leaves can be laid on vermiculite in a warm place, the ribs cut at junctions and fastened down with toothpicks or hairpins. The rooting medium should be porous and not too wet. A glass or plastic cover placed over the leaf sections will provide a moist atmosphere without having to wet the leaves, which often leads to rotting. After the callus has formed and roots develop, young plantlets will soon sprout. This method of propagation is important where rapid reproduction is wanted, while preserving the character of complex hybrids which may not breed true from seed.

Propagation by root cuttings is sometimes possible. The roots of plumbago, pelargonium, clivia or clerodendron are cut into 3 - 5 cm sections in early spring and shallowly laid into damp peatmoss with sand. Buds will soon break, developing into a young plant. If geranium plants are buried upside down, plantlets will sprout from the roots.

RHIZOMES, TUBERS, BULBS, AND CORMS

Rhizomes are swollen root stocks or underground surface stems, which are not roots, but storage organs of food and are provided with prominent leaf buds or eyes from which the new plant will sprout and with roots attached as food gatherers. Typical surface rhizomes are found in many ferns, such as the rabbit's foot fern. Many gesneriads principally achimenes, gloxinia perennis, kohleria and smithiantha produce pine cone-like scaly rhizomes and can be propagated both from rhizomes as well as from individual scales.

Tubers are modified swollen underground stems or thickened branches similar to a rhizome but shorter, beset with buds. Tubers store reserve food for the plant to use during dormancy. For multiplication they may be divided into as many pieces as they have eyes. Tuberous begonia, gloriosa, sinningia, reichsteineria, caladium, etc.

Bulbs are extremely short stems made up of closely packed fleshy scale leaves attached to a comparatively small basal plate of solid tissue, from which roots are produced. Eucharis, amaryllis, clivia can be divided after flowering by breaking the old bulbs and bulblets apart. Many bulbs propagate naturally by production of tiny bulbs between the scales, eventually breaking the mother bulb apart, or bulblets may form on the outside of the old bulb.

Corms are also short, fat underground stems, like bulbs, but differ from a bulb in that food is stored in its centre, not in the scales and with the bud forming on the top (crocus, freesia). New corms form on .top of the old one by the end of the season's growth and the original corm dries up.

One of the simplest methods of propagation is Division. All plants that develop multiple crowns may be divided into several individual plants by pulling apart, splitting or cutting the plant at the base into as many divisions as it has growth centres. Many houseplants can be multiplied in this manner and care must be taken that each section is worked loose so that it retains all the original roots that are attached to it for prompt potting in individual pots. (Ginger, calathea, cyperus, aspidistra, clivia, primula, streptocarpus and many ferns).

Propagation is a miracle of rebirth, the creation of a new plant. There is something so fascinating in seeing a houseplant grow up from a cutting which we ourselves have managed to root. It is also a cheap and simple way of increasing your collection of favourite plants.

Please contact the OHS or the author if you wish to republish these articles. © Ottawa Horticultural Society

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