Propagation 101 – now is the time to have a crack at making cuttings

By | October 19, 2011

Be brave – take Cuttings

Rooting Gel

Rooting Gel

This is the time of the year for reproducing your plants. Nature plants her seeds in the autumn after all – the ground is warm and the plants are still awake.

The team on Gardener’s World have been focusing, however on vegetative reproduction. Taking rose cuttings, dividing perennials etc. so I thought I’d put together a summary for you.

At this time of year we’re looking mainly at semi-ripe and hardwood cuttings. The softwood cuttings on this years growth are taken in late Spring.

The reason that we want to make cuttings is that we can greatly expand the number of plants we have in our garden inexpensively. The reason that we can make cuttings is that thanks to the wonders of nature a plant knows which way up it is.  Plants produce Auxins at the apical tip. These plant hormones feed down the stem and ensure that the apical bud continues to grow by inhibiting the growth of lateral buds. That’s why pruning results in a bushier plant. It will promote rooting if its concentration is greater than the cytokinin hormones that are generated in the roots. If they are about the same then it will favour production of xylem – the woody tubules that the plant uses for hoisting water from the ground to the leaves.

So – to make a cutting we want to retain the apical bud if possible or at least cut the plant above a node. At the bottom of the cutting we need to make sure that the auxin level is high – which is why people use rooting powder or a purpose made gel like Root!t. Other things that cuttings like is a high humidity to keep the (turgor) pressure in the leaves up and a means of sealing the bottom cut so that air doesn’t get into it. Left to its own devices the plant can plug its own wounds using a compound called callose which is like cellulose only different (believe it or not that’s what my D Phil was about but I won’t bore you with it here).  However if you use a gel like Root!t it will help the sealing process.

One way of keeping the humidity up is to use a propagator – either a simple one or a heated one. If you are working on a larger scale you might consider a mister. Here in the Glasshouses we create a tent with polythene over the propagation bench. Or you can use polythene bags at a pinch.

It’s important to keep everything clean and to use sharp knives and scalpels. You need to keep them moist and if possible cut them first thing in the morning (allowing for frosts of course). This will help the plant not to wilt too much. You are going to injure it so you need to give it the best chance you can to recover.

So what do you do?

You take different types of cuttings at different times of the year. These are known as softwood cuttings which you would take in Spring, semi-ripe cuttings taken in August – mid October and Hardwood cuttings taken after the leaves have fallen.

Semi Ripe Cuttings

Taking Cuttings

Taking Cuttings

In the second half of this  article I’m going to cover semi-ripe cuttings since we’re just about in time to do these followed by hardwood cuttings in the next article.  The softwood ones will be the third in the series

However the absolute basics of cutting are

You cut below a bud horizontally. For best results cut with scissors or secateurs first to seal the cut and again with a really sharp knife just before you pot it. This cut is square. At the top end you either include the apical leaves and between 2 and 4 nodes depending on the plant or you make a sloping cut above a bud. You keep the cuttings moist until its time to pot them. Then you seal the bottom with Root!t Gel which contains auxins and then keep them moist and sheltered over the winter.

Semi-ripe cuttings are an easy way to propagate a wide range of hardy climbers, herbs, ground-cover plants, shrubs and trees – especially evergreens – without the need of special equipment or skills. This technique is suitable for berry fruits, Ceanothus, Forsythia and Philadelphus.

So before the leaves drop off – now is the time to get organised.  We have maybe a 10-14 day window before we get a frost severe enough to start the process in earnest. Our Mulberry tree last year dropped the lot overnight.

This is the RHS list of plant suitable for semi-ripe cuttings.

 

GroundcoverLonicera pileata, periwinkle, Rubus tricolor and calycinoides.

Climbers:  ivy, passion flower, Solanum and Trachelospermum

Evergreen shrubs : Artemisia, Berberis, Brachyglottis, Camellia, Ceanothus, Choisya, Cistus, Convolvulus cneorum, Erica, Hebe, Fatsia, Mahonia and Viburnum.

Hedge plants: box, cherry laurel, Escallonia, holly, Lonicera nitida, Portuguese laurel and privet.

Perennial Herbs : bay, hyssop, lavender, rosemary, rue, sage and thyme.

Trees : Holly, Magnolia grandiflora, evergreen conifers.

What to do.

Take the cuttings from this season’s growth. The base of the cutting should be hard, while the tip is still soft. This material is available in late summer until mid-autumn.

Select healthy shoots free from pests and diseases that are more horizontal in habit with short internodes (gaps between the leaves). You can encourage these by pruning some plants really hard in the spring.

Types of semi-ripe cuttings:

  • Standard:  cut just below a leaf to leave a cutting of 10-15cm.
  • Heel: (where the cutting is pulled away with a piece of the stem) suitable for – Ceanothus and Berberis and Roses.
  • Basal: cut the shoot at its base. Suitable for Broom.
  • Mallet: Plant a leaf as a cutting, burying it with a piece of stem. Used for Mahonia

Taking a basic semi-ripe cutting

  • Use this season’s growth and remove using sharp secateurs.  This will seal the cut
  • Put in a plastic bag straight away. – pot the cuttings within 12 hours.
  • Trim to 10-15cm (4-6in) in length, cutting just below a leaf node. Next, remove the lowest leaves and the soft tips. Leave about four leaves. Cut the leaves in half to reduce water loss if they are big.
  • Dip the bottom of the cutting in Root!t gel, ensuring that the cut is well covered. For difficult-to-root shrubs, such as Magnolia grandiflora, try ‘wounding’. This is the removal of Insert the cuttings into suitably-sized containers filled with 50 per cent free-draining potting compost and 50 per cent sharp sand or perlite. Water well and allow to drain.  Alternatively use purpose made plugs like those in the root!t range.
  • Put in a greenhouse. They need to be warm and light but out of direct sun.  They need to be kept damp but not waterlogged. Autumn cuttings benefit from a heated propagator like the Stewart ones.

If the plants are hardy you can just put them straight into a spade cut like Monty Don did on Gardener’s world and leave them under a cloche for the winter.

Next post  on the subject will deal with Hardwood cuttings

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