Increasing Your Stock Of Climbing Plants

Getting something for nothing is always an appealing idea, but growing your own plants from seed, or propagating them from cuttings, also gives you immense satisfaction.

Growing from seed

Starting climbers and shrubs from seed can be a long-winded business except in the case of the herbaceous kinds such as the nasturtium (tropaeolum), the sweet pea (lathyrus) and the morning glory (ipomoea). If you are prepared to wait for plants of a reasonable size, you can also grow a number of berried plants from seed with relative ease – berberis, for instance.

Seeds for annual climbers can be started off under cover in the spring, to give them a good start. Seeds’ requirements are relatively simple: they need moisture and warmth, preferably bottom heat, to start them off. Once up, they need light. If you have not got a purpose-built propagator or seed starter trays, then put the seeds in pots encased in plastic bags to keep the moisture in, to start them off. The easiest way to raise climbers and shrubs from seed is to sow them in small peat pots or soil blocks so they can be transferred outside without too much root disturbance. Hard-coated seeds, like those of the sweet pea (lathyrus) and the nasturtium (tropaeolum) need to be soaked first to speed up lathyrus sweet peagermination, or stratified – scratched to let the moisture in. The easiest way to do this is to line an old coffee jar with coarse sandpaper, rough side in, put in the seeds, screw on the lid, then shake the jar briskly.

Seedlings should be thinned out once they have their first pair of leaves. Take care not to disturb the roots of those you wish to keep and pluck out the weaker and supernumerary plantlets . Half hardy annuals such as the morning glory (ipomoea) and the glory vine (eccremocarpus) should not be put out of doors until all danger of frost is past and, if they have been kept in the warm, they must be ‘hardened off’ first – transferred to a cooler frost free place to acclimatize themselves.

Cuttings

Many, in fact most, climbers and shrubs can be easily increased by cuttings and these are usually taken in midsummer. Taking cuttings is the fastest way of adding to your stock since they have a flying start compared with plants grown from seed, and provided you guarantee safety in numbers, by taking more cuttings than you need to allow for a mortality rate, there is no reason why you should not grow some healthy new plants. Some cuttings ‘take’ so easily that you can root them in a jar of water. Others, usually from evergreens, take much longer to get going, so it is a good idea to set aside a small bed in the garden for them.

There are three types of cuttings: softwood – young shoots which are taken in the spring; hardwood cuttings – mature pieces of stem which are taken in the autumn; and semi-hardwood cuttings – the most usual way of propagating most climbers and shrubs.

Semi-hardwood cuttings are taken from shoots which were new in spring but which have now become firmer and harder. They are taken from the parent plant by removing a shoot that is anything from 7.5-15 cm (3-6 inches) long. Pull this off the plant with a downward motion, taking with it a small ‘heel’ off the main stem – in other words a piece of more mature growth. Take off any leaves that are in the lower two-thirds of the cutting, leaving just the top third; dip the cutting in a hormone rooting compound, then put it, together with several others, round the rim of a pot which contains a 50-50 mixture of peat and sand.

While the cuttings are making roots their water supply is of prime importance. In taking the piece of plant from its ‘parent’ you are cutting off the water supply to the leaves that normally comes from the roots, but the leaves are still losing water in the usual way by transpiration, and the cutting will dry up and die unless certain steps are taken. The number of leaves is reduced: that is why those on the lower two-thirds of the plant are taken off, and you now have to give the plant an atmosphere of moist air in which to live while the roots form. This can be done by frequent misting, but the easiest way to tackle it, if you have not got a propagator, is to make a ‘tent’ of plastic over the pot: simply up-end a clear plastic bag over the pot, securing it round the rim of the pot with an elastic band. To keep the plastic off the plants, push a wire hoop or a couple of twigs into the soil in order to turn the plastic bag into a tent.

Layering

This is another method of propagation that suits some plants: Wisteria sinensis and Forsythia suspensa, both of which can be increased by cuttings, can also be layered; so can the mag- nolia but it is a slow process, taking two or three years for rooting to be certain.

The method is quite simple: you choose a likely looking, conveniently placed shoot, cut a small slanting nick in its underside – I.e., the ground-facing side, about halfway along it, dip it in hormone rooting compound, then ‘peg’ it to the ground or into soil in a conveniently placed flowerpot, using a hoop of wire or, in the case of smaller-scale plants, a large hairpin. Pile soil over the pegged portion of stem and after a while it should root. Once the first shoots appear and you are sure that it has ‘taken’, the stem can be severed from the parent plant.

Air-layering

Another method of layering which can often be used for climbers if the piece you want to layer is well off the ground, is air-layering. In this case, you nick the stem in the way described above, dip it in rooting compound, then wrap it in moist sphagnum moss and cover it tightly with clear polythene. Make sure that air-layered stems are tied up in a curve so that the nick in the stem remains open, or put a sliver of wood – a matchstick, for instance – in the nick before you wrap the stem in the moss. Once roots are visible pushing through the moss, remove the covering and sever the new plant below the level of the wrappings.

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