Layering is a great way of propagating many hard-to-root shrubs. Hannah Stephenson shows you how to tackle problem plants.
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, 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 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.
Best of the Bunch
These evergreen beauties produce gorgeous, blousy blooms in early spring and have glossy foliage all year round and an attractive bushy growth habit reaching 2m and more. They don't, however, relish really cold, windy weather, so they are best grown in the shelter of other shrubs, in a pot in a sheltered spot, or close to a wall.
Camellias like acid soil, so if you are growing them in a container, use ericaceous compost. Most are varieties of C. japonica and popular favourites include the pink 'Elegans' and the semi-double red 'Apollo'. The hybrids of C. williamsii are hardier than C. japonica, and good varieties include 'J.C. Williams', which bears pale pink blooms, and C. 'Leonard Messel', which has bright pink, semi double flowers.
Good Enough to Eat
Purple Sprouting Broccoli
Purple sprouting broccoli is the hardiest for growing at home and will survive heavy soils and cold areas.
Early purple sprouting broccoli is ready to cut in February or March, while late purple sprouting can be harvested in April. Seeds can be sown thinly in 1cm trenches 15 cm apart from mid-April. They should be ready to transplant when they are 8cm high. Water the rows the day before you move them to their permanent spot. Hoe regularly and protect from birds.
Water in dry weather in summer and give a liquid feed fertiliser occasionally. As it turns cooler in autumn, draw up soil around the stems and stake the plants if necessary. Harvest the broccoli when the flower shoots (spears) are well formed but before the small flower buds have opened.
What to do this week
- Prick out seedlings before they become overcrowded.
- Take hardwood cuttings of shrubs.
- Be vigilant with pest control in the greenhouse. Warm March days under glass can encourage a population explosion of many greenhouse pests.
- Mulch beds and borders while soil is moist to reduce watering and weeding later on in the year.
- Don't rush to sow annuals. If the soil is too cold, wet or dry, germination will probably be poor.
- Start feeding your pond fish in moderation when the water temperature stabilises at 7C for about a week.
- Check borders for plant losses and plan to fill any gaps.
- Lift and replant snowdrops and winter aconites before the leaves die down.
- Prune any overhanging hedges, trees or shrubs encroaching on borders. If you have a heated greenhouse or good kitchen windowsill, save a packet by buying plug plants early for summer.