Before beginning to take cuttings, remember to check PBR – Plant Breeders Rights. If the shrub is protected under patent rights, it should not to be propagated by anyone other than the PBR holder.
As plant growth slows down, the current year’s stems start to harden up and become
‘semi-ripe’ . Cuttings taken with these stems generally have a good success rate. The stems have more stored food than a softwood cutting. However, unlike hardwood cuttings, they still have foliage, so do suffer from water loss.
Many deciduous shrubs can be easily propagated by this method. For example, Deutzia, Weigela, Philadelphus, flowering Currants.
Ideally, one would have planned ahead and pruned and then fed at the end of the dormant season to encourage lots of long new stems to use as propagation material in the late summer. But sometimes cuttings need to taken at short notice, generally this does not present problems.
There are four different types of semi-ripe cuttings:-
- The basic method works on many shrubs, deciduous and evergreen. This is the one detailed below as it is the most useful.
- Heel cuttings are where the cutting is pulled away with a piece of the stem. Shorter side stems are often removed this way.
- Basal cuttings are where the shoot is severed at its base.
- Mallet cuttings are where an individual leaf with a piece of stem attached is used.
All of these cuttings may be put into pots or planted directly into the ground.
Equipment
- clean, sharp knife
- bypass secateurs
- plastic bags
- bucket of warm water, to keep cuttings moist when back at the shed
- hormone rooting powder / gel (optional) synthetic or organic
- small dish to hold the rooting hormone
- dibber (or pencil!) to make planting holes
- fine sand – a shallow layer on top of soil / potting compost
- labels, pen / pencil
- record book (optional / if required)
If planting in pots –
- potting compost – your favourite mix for cuttings
- pots
If planting into the ground –
- prepare a shallow trench or cold frame soil – ensure good drainage
NB remember to clean and sterilise equipment before taking cuttings. This should also be done between cuttings if they are from different plants.
Parent plant
As the cuttings will have the same characteristics as the parent plant, it makes sense to consider the desirable features that you would like to see in the offspring. For example, bushy growth habit, disease resistance, long flowering period.
The parent plant should be mature before cuttings are taken, and, ideally, you should water it 12 – 24 hours beforehand. Cuttings are best taken in the morning when the plant is most turgid. Do not remove more than 20%-30% of the plant at any one time.
Cuttings can be taken from the main stem and / or from side shoots, depending on the growth habit of the shrub. Be sure to take a longer cutting than you’ll eventually plant.
When cut from the parent shrub, place the cuttings into a plastic bag straight away. Keep the bag in the shade until you are ready to prepare the cuttings. If the weather is hot, they can be placed in the fridge.
Although it is best to deal with the cuttings immediately, it is possible to keep them for about 12 hours. If they are stored in the fridge, a little longer is possible, but not recommended practice as the plant material degrades.
Method
When you’re ready to prepare your cuttings, transferring them from cool place and standing the cut ends in warm water for an hour seems to improve the success rate. Take each cutting out one at a time to work on.
Remove the tip of the cutting if it is soft growth. Hopefully, your stem cutting will have an apical bud which has ‘set’, in other words, it has stopped growing for the year. In which case, leave it on. If you’re not sure, then remove the apical bud, as otherwise it may impede the formation of new roots.
Remove the leaves from at least the lower half of the stem. There shouldn’t be more than 4 leaves remaining. If the leaves are large, then cut them in half horizontally. This is to reduce respiration rate, and the cutting drying out before sufficient roots have formed.
Reduce the cutting in size to 4 -6 inches / 10-15 cm long, making the base cut just below a node. Personally, I prefer to make this cut with a knife rather than secateurs as a clean cut seems to aid formation of roots, by callousing over more quickly in the first instance. It is from the callous that new roots will develop.
In pots – make holes in the soil around the edge of the pot for the cuttings.
In the ground – the cuttings should be placed 3 – 4 inches / 8-10 com apart
Dip lower end of cutting into hormone compound if using.
Slip into hole so that the nodes of the removed lower leaves are level with / just below the surface. As these contain potential root cells, it gives more options for root development. Firm the soil around the cutting.
When all your cuttings are planted, water well. Label them (Do this as you work if planting cuttings with similar leaves) Cover them to maintain humidity until roots form.
Bottom heat generally helps autumn cuttings to root more quickly but is not essential for hardy shrubs. Even with heat, some cuttings may not fully develop roots until the following spring.
Aftercare
Check daily at first to ensure compost / soil is moist.
Cuttings may wilt slightly at first but should be upright by day 3 at the latest. Allow ventilation at this point. If they wilt again, then go back a stage.
Keep the cuttings shaded; temperatures above 24 ˚C can inhibit rooting and increase the likelihood of damping-off.
Leaves may drop off (some shrubs are more prone than others) If there is no other sign of pest or disease it should be fine. Remove the fallen foliage.
Problems
Fungal moulds and rot can be prevented and the affects reduced by –
- regularly removing diseased and dead material
- ensuring good ventilation to help remove excess moisture
- keeping the soil damp
- preventing too high a temperature for hardy shrubs
Leaves looking burnt at the edges suggests that roots have not yet formed.
If several cuttings are wilting, then the problem is probably environmental. However, if you took cuttings from a less than healthy parent that could be the issue.
Ongoing Care
Late summer cuttings will need frost protection over winter. This could be a cold frame covered with hessian or fleece, a cool greenhouse or polytunnel.
Remember to check on them regularly.
Planting out
Once the last frost has been, begin a hardening off process. The plants are best left where they are in the ground until the autumn. This allows a strong root system to develop over the growing season.
Cuttings planted in pots will probably need to be potted on into larger and / or separate pots during late spring.
Continue to check regularly, watering and giving a spring feed.
Once the young plants have dropped their leaves in the autumn, and have gone into dormancy, they can be planted out into the border. If larger specimens are required, they can be moved into a holding bed for another year.
They are still young plants and should be given extra care until fully established.
Marie Shallcross
Plews Garden Design and Consultancy