Boost your plant stock by layering

Rhododendron flowers. Photo: PA Photo/thinkstockphotos
Rhododendron flowers. Photo: PA Photo/thinkstockphotos

There are some plants that just don’t do very well with traditional propagation from cuttings - rhododendrons, camellias, honeysuckles and daphnes are just a few

But many ‘problem plants’ can be propagated by a method called layering.

Unlike cuttings, which have to survive on their own, simple layering induces roots without actually cutting the shoots off the parent plant. And because the shoots have a source of food and water from the parent plant while they are forming roots, they have a good chance of survival.

Simple layering is best done in spring or autumn, when the plant is actively growing. Choose a branch that is no more than two seasons old, which is at ground level or can be bent to touch the soil.

Dig the ground over where the branch is to connect with the soil, making a small hole where the stem will be positioned, adding a little compost and sharp sand to form a free-draining area to encourage rooting.

Strip the branch of leaves within 15cm on either side of where the stem is to touch the soil, to concentrate the plant’s energies on creating new roots, then cut a slit in the stem and push the damaged stem into the hole, pegging it down with a forked stick or U-shaped piece of wire to hold it down, ensuring the wound is in direct contact with the soil.

Peg the shoots upright, so they will grow upwards and be easier to lift later on. If you need to, stake the shoot beyond the rooting stem so that it isn’t damaged by wind rock (when roots are loosened because of strong winds). Cover the stem with more compost and water in to settle the soil.

It’s wise to put a large stone over the top, both to hold the layer in place and to conserve moisture. It may take the layer up to two years to root, but when it does it can be detached and replanted.

Other shrubs suitable for layering include magnolia, syringa, forsythia and viburnum. Upright plants whose branches won’t easily connect with the soil, such as witch hazel, acer and jasmine may be more suited to air layering, a technique whereby the compost is taken to the layer rather than the other way round.

Start by making a cut in the stem just below a leaf joint and passing vertically through it up the stem. Sprinkle hormone rooting powder on the cut, keeping it open with either a matchstick or a small amount of moist sphagnum moss. Wrap more moss around the joint and then wrap the whole thing in clear polythene, tying it top and bottom. After a while, roots will form and you should see them through the polythene.

Once the shoot has rooted, detach it from the parent by cutting below the rooted section using secateurs, then pot up the detached plant in the normal way.

To increase stocks of blackberries and hybrid berries, try tip layering. In mid-to-late spring, choose a long arching stem that easily reaches ground level. Bury the tip of the shoot 7.5cm (3in) under the surface of the soil. Peg it down (if necessary) with a loop of thick wire. Water if dry. Roots should develop from the shoot tip by the following autumn or spring.

Serpentine layering is more suitable for climbers such as clematis, jasmine, wisteria and honeysuckle. It involves looping the stems of climbers in and out of the soil - so that you end up with a sort of Loch Ness monster effect - to encourage roots to develop at several points along the stem. The technique is similar to simple layering, although thin-stemmed climbers don’t have to be wounded.