HOME PROPAGATION OF HOUSEPLANTS

There is a sound economic reason for propagating your own plants, but just as important is the satisfaction derived in the process. Although it is inevitable that we have to buy many of our houseplants, there is something special about a plant you’ve raised yourself -whether from seed or a cutting. Raising your own plants saves money in two ways – those you can grow from seed will probably yield dozens of plants for less than the cost of one grown specimen, and those raised vegetatively will provide plenty of ‘barter’ material for exchanging with friends. Most of the plants grown in our homes are easy to propagate, and it should be possible to produce an abundant supply of young plants to give to friends. Indeed. some are so prodigious that the offspring can be an embarrassment. Some methods of propagation, such as

air layering, do not greatly increase the stock, but are a practical way of maintaining fresh, well-balanced plants as the older ones pass their best. Losses of mature specimens are inevitable at some time, and having a few replacements coming along is always a wise arrangement.

It is perfectly possible to propagate a vast range of plants with no special equipment at all, but a heated propagator will make it all easier and extend the range of plants you can try. A propagator is especially useful for germinating seeds. Even a small propagator will enable you to produce an amazing number of plants, for the warmth is required mainly for germination, and once the seedlings are growing well they will usually tolerate room temperatures. Cuttings are likely to benefit more from the close atmosphere of a propagator

than the warmth (especially as many cuttings are rooted during the summer months), and they will root readily in the high humidity.

The humidity so vital for most cuttings can be provided at less expense by enclosing the pot in a plastic bag, forming a lent. There are various methods: the pot can be placed in the bag, which is inflated and sealed with a twist tie; four small sticks can be pushed into the pot and the bag pushed over the top and sealed round the pot with an elastic band; or the containers can even be placed in plastic bags and suspended with pegs from a line. An aid of a different kind comes in the form of rooting hormones. There are many cuttings that will root without these, but with more difficult subjects a rooting hormone will certainly speed root formation and may even make the

Plant propagation is both rewarding and easy – only a few simple tools are needed.

difference between success and failure. A real luxury is a mist unit, which will keep the leaves constantly moist by misting them with a fine spray of water whenever they are about to become too dry. These can be expensive, and are usually used in a greenhouse, but they are equally useful for rooting cuttings of all kinds, whether tender plants or hardy shrubs or trees.

Even the most elaborate aids to propagation will be of limited use unless a suitable rooting medium is used. In the case of seeds this means loam or peat-based seed compost. The brand doesn’t matter much – what does, is that it has been formulated for seed-sowing and has been sterilized in the case of loam-based types. Some proprietary peat-based composts are suitable for seeds or cuttings, and are very successful provided they are not allowed to dry out. Another excellent rooting medium, because it provides an open texture and plenty of air spaces, coupled with a high moisture-holding capability, is vermi-culite (sometimes used for insulating lofts). Failing that, a mixture of equal parts peat and sand is often satisfactory. Because the rooting medium normally contains little reserve of nutrients (sometimes none) it is important to pot up the cuttings as soon as they have formed sufficient roots to be moved safely. This time it is important to use a proper potting compost.

There is always the temptation to root easy plants in a jar of water – it’s fascinating to watch, and you know what progress is being made! But it is important to pot the plants while the roots are still tiny, ideally just as they are forming.

PLANTS FROM SEED

Seeds provide an inexpensive and interesting way to raise new houseplants, and most of those widely available germinate easily. A few seeds, however, may need a little help. Some germinate better if prechilled by placing in a fridge, between sheets of damp blotting paper, for a few days before sowing; a few need a period of high temperature to break dormancy, and

Step One: Place drainage crocks at the bottom of the box, fill to within about 18mm Qin) of the top with a seed compost, and firm gently.

Step Two: Water the compost then sprinkle the seeds thinly over the compost (mix with a little sand if the seed is fine and difficult to handle), or press large seeds into the surface. It sometimes helps to sow in small drills. Cover with enough compost to bury the seeds with their own depth of compost. If the seeds are large, the compost can be watered again from the top using a fine rose. With fine seeds that are lightly covered, sufficient moisture will penetrate from the damp compost.

Step Three: If an electrically-heated propagator is not available, place in a warm position and cover with a sheet of glass or slip into a polythene bag, ensuring the material does not touch the compost, and cover with newspaper. Turn the glass or polythene each day to eliminate condensation.

many with hard seed coats will germinate better if soaked in warm water for 24 hours. Hard coats can also be made permeable by rubbing lightly with sandpaper.

Light can also be important. Begonias require light for good germination, while Eccremocarpus scaber needs darkness. Always read the directions on the seed packet before sowing.

LEAF CUTTINGS

Increasing houseplants by leaf cuttings is quite easy, and from one leaf many new plants can be grown. Mature and healthy leaves should be used. Leaves which are very old and tough will take a long time to form roots. Plants suitable for this form of propagation are streptocarpus, gloxinias and some large-leafed begonias.

Sever the leaf-stalk low down near the base of the mother plant. Then, cut off the stem close to the eaf, and with a sharp knife or razor-blade slit through the veins on the underside of the leaf. Fill a large pot with John Innes seed compost, firming the soil to within 12mm (Jin) of the rim. Thoroughly water the soil and allow the compost to drain. Place the leaf on the compost, with the cut surfaces downwards, and use pieces of bent wire to secure it to the compost. The pot can be placed in a propagation case or a plastic bag. Three or four canes inserted into the compost will keep the bag off the leaf. When large enough to be handled the rooted plants can be potted individually

CUTTINGS

Many houseplants root easily and quickly during spring and summer months. Some plants can be increased by having their stems or shoots inserted into a peat-based compost, while others, such as peperomias and saintpaulias (African violets), root easily from the tips of their leaf-stalks (the young plantlets appearing at the base of the cut stem once the roots have had a chance to form). The botanical term for this method of propagation is leaf-petiole cuttings and it is an excellent method for suitable small-leaved plants, enabling a number of cuttings to be taken without spoiling the plant.

When increasing plants by this method use only young and healthy leaves. Cut leaves from the parent plant as close to their bases as possible, so that short stems are not left. Then cut the stems to 4cm (1 Lin) long.

Dip the end of each leafstalk in a hormone rooting powder to ensure that roots are quickly formed from the cut ends. It may be necessary to moisten the cut ends to enable the hormone rooting powder to stick to them.

AIR LAYERING

This distinctive form of propagation is useful for giving plants which have become long and leggy – with an expanse of bare stem making them look unsightly – a second life. Codiaeums, cordylines and the rubber plant Ficus elastica benefit from air layering. The Chinese have used this method of increasing plants for many centuries, and since the introduction of houseplants in their millions during recent years it has been employed to regenerate plants which have grown too high to be pleasing or practical in a small room. Air layering is sometimes called ‘ringing’, because one method involves the removal of a ring of bark from around the stem. The method most frequently used, however, involves slitting the stem. Eventually, roots grow from the cut and the stem can then be severed from the parent plant.

During the spring and summer, cut a 6mm (-^in) wide strip of bark from around the stem, just below the lowest leaf. A better way, however, is to cut a slit in the stem in an upward direction. Do not cut right through it. This method is better than ‘ringing’ the stem, as it allows nutrients to pass up the stem to the leaves to keep them in a healthy condition. With ‘ringing’, the passage of nutrients to and from the roots and leaves is restricted, especially during spring and summer when the plant is growing more vigorously. Before cutting the stem, ensure the plant has been well watered, as those lacking water will not root so rapidly. Avoid air layering in winter.

Insert the cuttings into a pot of John Innes seed compost, firming them well. Give them a good watering and place the pot in a polythene bag. Three or four short sticks can be used to keep the bag off the cuttings.

them. Trailing stems are pegged into the soil using bent pieces of wire. Once roots have formed the plants are cut from the parent and potted up.

Tie polythene around the stem just below the cut, and pack it with moist sphagnum moss or damp peat, seal at the top. In about ten weeks roots w form. Remove the polythene, sever the stem and pot up the rooted plant

Use a match-stick to hold the cut edges apart, and dust the surfaces with a hormone rooting powder to ensure that roots develop rapidly. Use a small paintbrush for this.

LAYERING

Many plants can be increased by pegging a stem or shoot, that is sti attached to the parent plant, into compost to encourage roots

Saxifraga sto/onifera and the small-leaved ivy are two excellent plants for this form of propagation. If the runners are long enough, peg them into pots of John Innes potting compost No. 1. Keep the compost moist. When roots have formed the stems can be severed. Plants such as small-leaved ivies are best set in large plastic trays with compost or a peat-and-sand mixture packed round

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