Propagating plants from cuttings is very satisfying and can provide cheap plants to use or to share and give as gifts to others. You take semi-ripe cuttings in mid to late summer and into early autumn. Many plants can be propagated from semi-ripe cuttings and will be less likely to wilt than softwood cuttings taken from new growth earlier in the season. This is because the stem structure will be more developed and resilient. Plants that can be propagated this way include many shrubs and herbaceous plants such as Choisya, Viburnum, Hebe, penstemons and lots of culinary herbs like rosemary and sage.
A variation on the softwood cutting are heel and leaf bud cuttings, both of which are techniques also suited to this time of year when new growth contains an abundance of the hormones that plants require to re-grow roots and take on their own life. Plants such as Camellia, Pieris and Berberis suit these methods.
There are many plants that can be propagated using this technique. The internet and garden books will help identify which ones are likely to be most successful, but we feel that there is some fun and interest to be had by just simply giving it a go with plants you have in your garden. You could even try a few different types of cutting from each plant and compare results.
1. The first step is to identify a healthy stock plant to take the cuttings from. You are looking for plants that are disease free, healthy growing and not in bloom or currently producing seed heads or berries (although you can take off flowers, seed heads and berries and still be successful).
2. You are looking to identify growth from this year. This is most likely located at the end of stems and it can be interesting to notice how the stems change colour and woodiness (in shrubs) as they grow each year. In particular you are looking for side-shoots and leading shoots at the end of stems and branches.
3. Once you have a rough idea of how many cuttings you want to take, prepare the rooting medium. A compost for cuttings needs less nutrients and more structure than compost containers. There are many suggested ingredients that can be mixed to make a good medium for propagating cuttings, such as 40% loam with 40% perlite and 20% leaf mould. You can find all sorts of recipes online and old RHS books will suggest fine-grade pine bark. You can buy compost that has been formulated for cuttings and John Innes seed compost is recommended by many horticulturists.
4. Once you have chosen the compost, fill up seed trays (modular work best) or propagators or small pots with the mix as you would if you were sowing seeds. You are looking for the compost to be firm but not solid and for the top of the compost to be a few millimetres from the top of the tray. Water the compost so it is moist but not wet. Doing this first means your cuttings spend less time out of contact with moisture.
5. Now go back to the stock plants and identify the stem for cutting. Cut using sharp and clean secateurs, or snips for softer and smaller stems. Cut at the node just above a point where one form of the plant goes into another (new stem coming from main stem or leaf coming out of stem). You are looking to take cuttings at this time of year that are around 10-15cm in length. You cut at the node as this is where the largest concentration of hormones are stored within plants, and this will aid re-rooting.
6. Either take each cutting in turn and place in tray or propagator or continue taking more cuttings. If it will take you more than 5 minutes to collect all the cuttings then use a polyethene bag with a single spray of water or a few droplets added to keep the cuttings moist. Taking 3-5 or more cuttings from each plant you wish to propagate is sensible as rooting is not always successful.
7. Remove any side-shoots from each of the cuttings. Leaving too many leaves means more transpiration and moisture loss from your now tender cutting. You can use sharp snips, scissors or craft knives for this (be careful when doing this). Sometimes using a clean chopping board helps. Remove any leaves on the lower part of the stem as well. When doing this you are trying to cut up close against the main stem. Again, this helps maintain moisture and protects from disease.
8. If the cuttings stem is fairly firm (will be in shrubs, and sometimes is in herbaceous plants) then using the clean sharp blade, carefully remove the outer bark at the bottom of the stem 2-4cm long. This will encourage root growth.
9. Using a dibber or clean stick, make a hole in the compost wide enough for the stem and deep enough for around one third of the stem to be in compost. If you have cut at the bottom of the stem, the whole wound should be below compost level. Firm in gently and add more water if the compost has dried.
10. Repeat this with all cuttings leaving around about 8-10cm between cuttings, making sure leaves are not touching.
11. In most cases semi-ripe cuttings need to be covered with polythene or propagator lids to maintain moisture levels. There are some that will require the whole of winter in order to root and these tend to be left uncovered in a greenhouse or similar environment with moisture levels checked regularly.
12. Label or find another way to identify the cuttings and mark when you began the cutting process. As with lots of garden labelling, the date is as important as the name. Different plants take varied amounts of time to re-root, at least 3-4 weeks but many can take longer. You can check if they have rooted by giving them a very gentle tug from the leaf, or better still check for signs of root growth through the drainage holes.
13. Place the cuttings in a light and warm environment such as a glasshouse or windowsill away from direct sunlight. Keep checking the cuttings every few days to ensure they are moist and disease free. If any look as if they are wilting or dying despite good moisture, then remove them as they could infect other healthy cuttings.
14. Once you have some rooting, pot up into 1 litre pots with a multi-purpose potting on compost, allowing the cuttings to grow on for 2-6 weeks before planting into their final position.
Heel and leaf bud cuttings, referred to above, are variations on the semi-ripe cuttings theme that can improve your chances of success with certain plants.
Heel cuttings are so called as they involve removing a side shoot from the main stem by hand, gently pulling (peeling) from the top down so that a strip of bark from the main stem comes away too. This is the ‘heel’. The purpose of this is because the striped heel exposes the cambium layer which contains a high concentration of plant auxins (hormones) that will help roots to grow from the wound. The base of the heel can be trimmed if necessary before ‘planting’ as above for other semi-ripe cuttings. Heel cuttings are good for older, woodier plants (but not trees) and Sambucus and sub-shrub herbs like rosemary and lavender.
Leaf bud cuttings are especially suitable for climbing plants like clematis, camellia and Rhododendron, where the space between nodes may be too short to allow for normal cuttings.
Select a piece of stem that is not too woody or green and cut between nodes into sections. This way you can get many cuttings from one stem. Trim the top to just above the node that has a leaf coming from it. When planting the cutting make sure that the compost reaches the node as this is where the leaf bud is sited and it is from this that root growth will occur. The leaf may need cutting (or if there are multiple leaves, reduce the number) to reduce water loss through transpiration.
With all these semi-ripe cutting techniques, it is advised that you use a root hormone powder/liquid, although it is still possible without. Using the product according to the manufacturer’s recommendations will increase the chance of the cutting successfully rooting and this is likely more the case with semi-ripe cutting over soft or greenwood cuttings, as the stores of hormone at late summer are lower within the plants. The difficulty with the hormone products is that once opened they deteriorate quickly. Perhaps if you are taking a good number of cuttings or if the cuttings you are taking are important to you then it is a worthwhile purchase.