Propagation of Indoor Plants

Propagation of Indoor Plants

Propagation or simple plant reproduction is much easier than most people imagine. Of course there are exceptions, such as bougainvilleas or kentia palms, that require the knowledge and equipment of the expert, but a large number of plants can easily be reproduced without specialized knowledge and equipment. All that is needed is patience and a little care.

It is vastly satisfying to grow a plant from a small seed or tiny cutting. Some plants are propagated merely to increase a collection or to be given away, but others may have to be propagated to keep the strain going. Plants like poinsettias and aphelandras, soon deteriorate if allowed to grow too old, and the vitality of the stock is only maintained by the production of new plants from cuttings or seeds.

Forms of reproduction

There are two basic forms of reproduction in the plant world. The first is vegetative, which involves taking cuttings from stem, leaf or root; dividingof the plant, rootsor tubers, and air layering. The otherway is by sowing seeds or spores. The majority of house plants are propagated vegetatively, the use of stem and tip cuttings being most favoured, especially commercially. This is also one of the easiest of all methods of propagation. To get a good young plant it is essential for it to make roots as quickly as possible so that these can provide it with the nourishment it needs to make top growth of stem and leaf.

Ideal conditions

Most indoor plants will root quickly in a high temperature and with a high humidity. Commercially this is often done by placing the propagating beds over hot water pipes and having spray pipes that send out a fine spray of water at regular intervals. This equipment is expensive and difficult for an amateur to install and it is doubtful if it would be worthwhile in most cases. It is possible to make small propagators that are effective and very inex-pensive.

Simple propagators

The simplest propagator of all is made by placing the pot containing the seeds or cuttings in a plastic bag and tying up the top. Care should be taken that the bag does not weigh down on the cuttings. You can prevent this by placing a hoop of pliable wire in the pot to hold the bag up. Make another simple propagator by upending a glass jarovera pot; orputtingthe pot containing thecuttings or seeds into a larger pot, then placing a sheet of glass across the top.

Box propagators

A wooden box with sides about 150 cm (6 in) high and a sheet of glass over the top makes a good propagating box. Alternatively, if more light is required, use four sheets of glass of a similar height held together by wide transparent tape with another sheet across the top. If you want to use inexpensive materials that may be already to hand, try putting a large transparent plastic bag over a cat litter tray and supporting it in the middle with a milk bottle. With the additional help of a misting spray all these devices produce the humidity required.

Heating devices

Heat is also required underneath to warm the compost. It is possible to buy heating tapes or wires that can be placed in the bottom of your home-made propagator. These should, if possible, be thermostatically controlled and run off a transformer to make them safe. But, it is possible to improvise less expensively. A thick candle burning beneath a metal sheet under the propagator box can be effective. Placing the propagator box on top of the domestic boiler is another method. In a greenhouse, placing the box above a paraffin heater is a good idea. Alternatively, there are on the market a number of propagators complete with heating tapes. Choose carefully particularly with regard to size, because it is easy to buy one that is too large.

Taking cuttings

Taking cuttings is the easiest way of reproducing most plants, and this is usually done with stem and tip cuttings. Take a strong growth (never use weak and straggly growth) and cut off 75-150 cm (3-6 in) with a sharp knife or secateurs. Remove all leaves and buds from the bottom half, dust the cut with hormone rooting powder and place in the rooting compost. Use special seed or rooting compost which is normally fine and contains only a little fertilizer. It is as well to add about a third of sharp sand to improve the drainage. The cuttings should be well watered and then placed into the propagator. Ventilate every day and spray overhead. Rooting time varies from variety to variety but it is often almost four weeks. When the root system of the young plants is apparent, pot up into small individual pots. Many plants can be rooted in water, which makes it easy to see when the roots form.

Leaf and root cuttings

Plants like sansevierias and dieffenbachia can be rooted by cutting the leaf or stem into about 10 cm (4 in) pieces and potting into small pots, then placing in the propagating frame.

Begonias and other large soft-leaved plants can be propagated by placing a leaf flat down on the compost and cutting the main vein in several places. Young plantlets will soon form at every incision. The last method is taking cuttings from roots, especially effective with cordyline. Cut thick pieces of root about 2.5 cm (1 in) long and plant horizontally in seed com-post, leaving part of the root uncovered. Keep the propagator at about 24-27°C (75-80°F). With all cuttings look out for damping off or rotting.

Air-layering

Another more complicated way of taking a cutting is by air-layering. You can use it to deal with a plant that has grown too tall or has lost all its lower leaves. The large-leaved ficus varieties and most dracaenas are suitable candidates for this type of propagation.

How to air-layer

Choose a clean part of the stem and make a shallow incision about 3-5 cm (1J-2 in) long. Dust the wound with charcoal or a fungicide and insert a small pebble or stick to keep the cut open. Wrap some wet moss around the wound and secure with string. Then cover the moss with polythene, tying it as tightly as possible without damaging the main stem above and below the moss. It is a good idea to support the plant with one or two stakes to help it cope with the extra weight and the weakness caused by the cut.

The new plant

After four to six months roots will be seen coming out of the moss on the side of the polythene. Cut the main stem directly below the polythene, dust the wound on the mother plant with charcoal or fungicide and cover the cut with cottonwool or sellotape to stop any bleeding. Then carefully remove the polythene from the top part. If any of the moss is not full of roots, remove that as well. Now gently pot up the rooted portion, taking great care not to damage the young roots. Water the plant and place in a shady place for three or four days. It can help to put the whole pot and plant into a polythene bag to maintain a high humidity.

The old plant

The top of the mother plant’s soil should now be changed. The plant will soon throw out young shoots directly below the top of its stump and grow bushy.

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