Cuttings are a way of removing part of a plant in order to obtain a new one.
It is important to start with a healthy parent plant, i.e. one without any insect pests or diseases. Once rooted, the cutting will grow into a lovely, healthy plant itself.
Another advantage of this technique is that it preserves some characteristics that may be lost when trying to grow a new plant from seed, such as the colour of a hybrid’s flowers.
How successful you are with this technique will depend on both the quality of the cutting and on how well you care for it afterward.
The length of a stem cutting varies depending on the type of plant. As a rule, take 2 to 4 nodes or a piece 5 to 15 cm long. It is best to use a very sharp, disinfected knife to avoid crushing the base of the cutting and to reduce the risk of contamination. When removing the cutting, cut just below a node or a leaf scar. There is no need to make a diagonal cut, as the larger wound will often only increase the risk of rot. Then remove the leaves from the base of the cutting to obtain a bare stem about 2 to 6 cm long. To increase your chances of success, use a rooting powder containing growth hormones.
During the cutting process, the leaves continue to lose moisture by transpiration, while the lack of roots limits the ability to absorb water. The water balance is disrupted and the cutting can dry out quickly. Removing some of the leaves is one way of preventing cuttings from wilting. Another method is to cover the container and the cutting with a clear plastic bag, to make a sort of mini-greenhouse. Poke a few holes in the plastic or leave it unsealed in a few spots to avoid excess moisture build-up, which would create condensation inside the bag.
All these steps apply for most plants. Cacti, except for tropical species, and succulents are the exceptions to the rule. For these plants, the cutting must be allowed to dry out before it is placed in soil, to allow the wound to heal completely. Otherwise, you will have problems with rot. It may take a few days to a few weeks for the scar to form, depending on the size of the cutting. Sprinkling the wound with powdered charcoal will reduce the risk of fungal infection. Finally, this type of cutting must not be covered in plastic.
- Cut below a node.
- Remove the leaf from the bottom node of the cutting.
- Dip the base of the cutting in rooting hormone powder.
- Fill a pot with a rooting mix. Poke holes in the mix with a pencil and insert your cuttings in the holes.
- Cover the cuttings with a clear plastic bag so that they won’t wilt.
Just a glass of water is enough for plants that root easily. This is not the best method, though, because the roots will be fragile and poorly adapted to growing in soil, increasingly the likelihood of transplant shock. It is a good method for plants that you intend to grow hydroponically. If you do try it, make sure that none of the leaves are submerged, or they will rot.
Packaged rooting mixes or peat-based potting mixes are suitable for most cuttings. If you would rather make your own mix, use perlite, vermiculite, coarse sand or peat moss. One, two or a combination of several of these elements usually gives good results. Fill the container to within a few centimetres of the top, then level and gently tamp down the mix. It will be difficult to water if it is too full. Stand the cuttings in the mix and gently firm it around them. For the first watering, you can immerse the base of the container in water for a few minutes.
The cuttings require sunlight in order to root. Put them in a bright spot, but not in direct sunlight, or they will dry up and wilt. Various factors, including the plant species and soil temperature, will affect how long it takes for roots to form on the cuttings. The ideal temperature is 25 to 27°C. It usually takes about three to four weeks for plants that root easily. Woody cuttings, like flowering maples and citrus, often take over a month to root properly. Once they are well rooted, transfer the cuttings to small pots 8 to 12 cm in diameter. You can put several cuttings together in one pot. To reduce transplant shock, keep the ball of rooting mix (peat moss, vermiculite, etc.) around the young plants’ roots.
Leaf cuttings have all the same advantages as stem cuttings. This is an easy way to propagate succulents. Just remove a healthy, well-developed leaf from the parent plant and let it dry for 24 to 48 hours for the wound to heal. Then insert the base of the leaf in a well-drained medium like sand- or perlite-based potting mix.
Some other plants, like African violets and peperomias, can also be propagated from cuttings by rooting a leaf and its leaf stalk in vermiculite, perlite or a 50-50 mix of the two.
Divide the plantlets once they appear and transplant them into moist peat-based mix.
Rex begonias can be propagated in two ways.
The first is to cut incisions in the leaf veins and then lay the leaf on a bed of moist peat moss. Hold it down with “U” shaped pins.
The second method involves cutting the leaf into wedges. Make incisions in one or two main veins at the base of each wedge.
Then stand these leaf wedges up in peat-based mix so that the vein incisions are in contact with the medium. Keep the mix moist until the cuttings form roots. Plantlets will appear within a few weeks.
No matter which method you use, once the cutting is well rooted, transfer it to a pot and care for it as you would an adult plant of the same species.
In the case of the sansevieria that has very long leaves, start by separating them into 5-10 cm sections before placing them in a rooting mix, respecting the polarity of leaf development.
Examples of indoor plants that are appropriate for cuttings:
- Schlumbergera (Christmas cactus)
- Senecio rowleyanus
Woody cutting (hormones)
- Nerium oleander
Propagation in water provided
Illustrations: Espace pour la vie/Audrey Desaulniers