How to Successfully Propagate Plants

Perhaps propagating from seed would appear to be the most obvious way to reproduce plants, but in many cases the plants produced in this way revert to their original form, so in the main it’s better to be concerned here with propagation by cuttings, layering, division and so forth.

Increasing plants by dividing them up is quite an easy process, especially in the case of hardy perennials with fibrous roots. Michaelmas daisies are good examples, as are heleniums and solidagos. Division is carried out either in the autumn, when plants have settled down for the winter, or in the spring, just when they’re starting to grow. Dig up the root clump (’clump’ is a good word to describe it!) and, with a couple of garden forks held back to back in the centre of the clump, ease and prise it apart, then sub-divide until the clump is in several pieces. Throw out old pieces of root and keep the good, strong, well-rooted pieces for replanting. Shrubs like spiraeas and berberis can be divided in this way, as can those that produce a quantity of stems rather than one main growth.

You can also divide plants with ‘woody’ crowns and growth buds, like lupins and delphiniums; those with rhizomatous roots, like the bearded irises; and tuberous-rooted plants, like potatoes, Jerusalem artichokes and dahlias. The ‘woody’ crowns are best divided in spring. Cut them in portions, each bearing a growth bud and roots. Cut rhizomes into three-inch portions, making sure each portion has a strong, new growth. Discard the old centres and replant horizontally. This should be done in July after flowering. The method of dividing the tuber types varies. Cut potatoes and Jerusalem artichoke tubers in pieces, each containing an ‘eye’. Dahlias should be cut in vertical sections, each including a strong growth bud and a portion of stem.

Next, to bulbous plants (for example, tulips, daffodils and gladioli). These produce offsets which can be seen attached to the parent bulbs or corms. Detached and replanted, these will develop and flower after a couple of years.

Suckers of roses and lilacs can be removed and used for propagation. So, too, can suckers from raspberries, almonds and sumach trees, to name but a few.

Another form of propagation is by grafting, which is the process of joining two living parts of plants so that they form a union, but lack of space precludes a sermon on this huge subject in all its aspects.

Now to cuttingsstem, hardwood, leaf and others… there’s a bewildering list of them. The portions of plants used consist, on the whole, of young stem-growths, semi-ripe wood, hard-wood, leaves, buds and roots.

Stem cuttings are half-ripe shoots taken from plants like hydrangeas or cistus, in summer. These should be about four inches long. Some require a ‘heel’ of old wood to be attached, as in the case of camellias, for example, but in most cases all they require after removal is to be trimmed just below a joint. Plant in a mixture of sand and peat, out of direct sun, and spray them daily until roots form. Incidentally, a good way of encouraging root formation is to cover pots with polythene bags, sealed and secured with rubber bands.

Hard-wood cuttings are taken in autumn from some trees, shrubs, climbing roses, hedges, currants and gooseberries. They should be about a foot long, cut just below a bud. All lower leaves are removed and the cuttings planted about six inches deep in sandy soil. Some, like hedging plants, gooseberries and currants, can be planted in soil with sand added, somewhere shady, in the open. Roots should form by spring.

There are many plants from which leaf cuttings can be taken – for example, gloxinias, begonias, saint-paulias. Insert the leaf stalk in a compost of peat and sand and flatten the leaf on the surface. Roots will develop from the leaf axil. In some plants – the begonia rex, for example – cuts on the veins on the underside of the leaf will encourage roots and thus form a number of new plants. Saintpaulia leaves should be left upright around the rim of the pot; plantlets will appear at the base.

Incidentally, hard-wood cuttings can be rooted in polythene. Lay them in a row on moist sphagnum moss on a strip of black polythene. Then roll it up like a cigar and secure it with rubber bands. You can use a similar method on house plants like ficus, which grow out of hand and threaten to go through the ceiling! Remove the leaves from a section of stem below the growing shoots. Make a slanting cut behind a bud and pack this round with moist sphagnum moss. Cover and secure this with a double layer of black polythene. Roots will form after a few weeks, when the top new plant can be carefully removed from the old and repotted. Spring is the time to do this.

And lilies? You can remove scales from lily bulbs and pot them upright in sand/peat compost. The new plants which develop should be potted separately.

Border carnations and pinks can be increased by ‘layering’ in July. So can strawberries and shrubs with low branches, like rhododendrons, clematis or forsythia. Select a young, non-flowering shoot and make an incision just below a bud, so that a tongue is formed. Strip off leaves in the immediate vicinity, spread a layer of rooting medium on the soil and, keeping the cut open in the stem, press it into the soil and rooting medium, anchoring it firmly with pegs. When roots have formed after about a couple of months you can sever it from its parent plant. Layered shrub cuttings may take much longer to become established.

Dried-out seeds collected from peas or beans, nasturtiums and soft fruit like tomatoes, strawberries and others are worth propagating. So too are pips from oranges, lemons and grapefruit.

POLYTHENE’ METHOD OF ROOTING WOOD CUTTINGS No watering is necessary, but when the process is completed keep cuttings out of strong light.

Pot on the cuttings when roots have formed—you’ll be able to see these through the polythene.

1. You need a strip of black polythene about eight inches wide, eighteen inches long. Place in it a layer of damp sphagnum moss

2. Lay cuttings on the moss, so they project beyond the polythene

3. Fold and roil the polythene over and over

4. Use rubber bands to keep it all compact

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