How to Multiply Your Shrubs

There are several ways to increase your shrub stock. The methods most widely used are hardwood cuttings, softwood cuttings, tip cuttings and layering. Of these, hardwood cuttings are the most likely to succeed, especially with deciduous shrubs. But with certain species, the other methods may produce better plants more quickly. The sections that follow describe how to carry out each technique, and which plants it works best with. Whatever method you choose, bear in mind these general points:

Collect more cuttings than you think you’ll need. The chances are that some will fail.

To give your cuttings the best possible chance, insert them in a half-and-half mixture (by volume) of peat and coarse sand.

Cuttings with leaves need a humid atmosphere, so keepthem in a propagator, or in a pot covered with a transparent plastic bag.

All cuttings require plenty of light – but not direct sunlight, which will scorch them. If you are uncertain which method to use, try hardwood cuttings first.

HARDWOOD CUTTINGS

In winter, when the plant has stopped growing, choose woody, hard stems of the current season’s growth and cut them near the base.

Trim each stem to about 20-25 cm in length. Remove the tip by a sloping cut, and trim the bottom of the cutting with a horizontal cut below a node – the spot where a bud or leaf is attached to the stem. Make the top cut just above a leaf node, the bottom cut just below a leaf node. Most cellular activity takes place at these nodes, and the trimming encourages the lowest node to throw out roots, the uppermost one to throw out shoots – increasing the chance of success. All leaves on the lower two thirds of the cutting should be removed. Large-leaved varieties tend to lose moisture rapidly: this can be reduced by slicing each leaf in half with a razor blade or sharp scissors. Do not remove all the leaves, though – they help to manufacture food for the cutting while it is rooting.

Plant the hardwood cuttings in a well-dug site protected from cold or drying winds and in semi- shade. Make a slit in the soil by inserting a spade tofull depth and then pulling forward a few centimetres. Lay a 5 cm layer of coarse sand in the bottom. Dip the bases of the cuttings in hormone rooting powder and plant them 6-8 cm apart with two thirds underground. Leave 40 cm between the rows. Push soil into the trench, water the cuttings well and tread them in firmly.

The quicker-rooting cuttings will be ready for setting in their permanent site after a few weeks. Slower-rooting species need a year or more. Be guided by the new growth that appears on the cuttings – ample, healthy, new growth is a sure sign that a cutting has rooted well.

Plants suitable for hardwood cuttings: Abel ia, berberis, Buddleia davidii, chaenomeles, datura, lonicera, privet, salix, sambucus, symphoricarpos and tamarix.

SOFTWOOD CUTTINGS

These cuttings are taken between early summer and autumn from the current year’s growth which has become moderately firm but is still growing. Softwood cuttings are green at the tip and the base. Semi-ripe cuttings are green at the tip and slightly woody at the base. Cut off sideshoots about 15-20 cm long, remove the leaves from the lower half and trim them horizontally just below the lowest leaf node.

Alternatively, pull off the sideshoots whole with a heel – a sliver of the main stem – attached. Whether the base has a heel or not, cut off the soft tip above a leaf node to leave a cutting 5-10 cm long. Dipthe base in rooting powder and insert the cutting in a tray or pot so that the lowest remaining leaves are just above the soil surface. Set the cuttings 2,5-5 cm apart.

Water them well and put them in a protected spot, or cover the pot with a transparent bag. Softwood cuttings take 3-9 months to root. Plants suitable for softwood cuttings: Al lamanda, arbutus, aucuba, barleria, brunfelsia, buddleia, buxus, callistemon, camellia (also suitable for leaf-bud cuttings, see cuttings), chaenomeles, choisya, cistus, cotinus, cytisus, deutzia, duranta, elaegnus, escallonia, euonymus, gardenia, garrya, hibiscus, hypericum, ilex, jasminum, ker-r, kolkwitzia, lavandula, lonicera, oleander, philadelphus, phloxes, photinia, potentilla, prunes (ornamental), pyracantha, rhus, roses, spiraea, viburnum and weigela.

TIP CUTTINGS

Try this method if you wish totakecuttings in early summer, though it demands constant care. Select shoots with 4-5 pairs of leaves and sever each shoot beneath the pair of leaves nearest the main stem. A 12 cm pot filled with cuttings compost or a half-and-half mixture of peat and coarse sand will take about 10 cuttings. Dipping thecuttings in rooting powder will help, but it is not really necessary.

Plant them in holes made with a dibber, firm in and water well. Cover the pot with a transparent bag and keep it in a warm spot, in a greenhouse or shade house, but out of direct sunlight.

Never let the compost dry out. The plants should root in 3-6 weeks, but they wi II need to be grown on in the pot for at least a year before being planted out. Because the cuttings usually grow very slowly, it is rarely necessary to replant them in other pots.

Plants suitable for tip cuttings: Abutilon, acalypha, callicarpa, conifer, erica, fuchsia, hypericum and mahonia.

LAYERING

Layering is an ingenious way of propagating shrubs without a shade house or greenhouse. Basically, a flexible branch is bent into the ground and encouraged to grow roots of its own before it is severed from the parent plant. One of the easiest methods is what horticulturists call simple layering. This is how it works:

Choose only first-year branches which have not yet flowered. In autumn, preparethe ground by fi lling a small hole with peat, coarse sand and’ soil, and bend a branch towards it, about 30 cm from the tip.

Strip off the leaves where the branch touches the ground. Notch the underside or twist it to injure the tissue. Dig a hole 15 cm deep in the prepared ground beneath the notched section and partly fill it with an equal-parts mixture of peat, soil and coarse sand.

Peg the notched part into the hole and cover it with the mixture. Stake the tip.

Make sure the spot never dries out, and within 12-15 months the layered branch should have rooted. You can check progress by gently scraping the soil away to have a look, and patting it back in place if the roots are still undeveloped.

Once the roots have formed a rootball I about the size of’the top growth of the tip above them, sever the new plant and its root from the parent branch and set it in its permanent home.

Plants suitable for layering: Azalea, camellia, cornus, cotinus, kalmia, lonicera, philadelphus, pieris, rhus and viburnum.

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