Many types of plants are grown from stem cuttings - including trees, shrubs, climbers, roses, conifers, herbaceous perennials, fruit, herbs, indoor plants and half-hardy perennial bedding plants. It is usually a very quick and successful method as most plants root very easily, many in a matter of weeks.
Even so, not every cutting will root successfully, so always take a few more than you need.
Until the cutting has rooted, it relies on the food reserves stored within the stem and leaves, plus food produced by the leaves (if present) through photosynthesis.
This has a bearing on the age and size of the stem used - the bigger the cutting (both length and width) the more food is stored and so the longer it can survive before rooting. The more leaves it has, the more food it can generate, but as plants lose water through their leaves, the greater the leaf area the more water it will lose, leading to a greater risk of drying out before rooting. So you have to make a judgement between the size of the cutting and its total leaf area. This comes with experience and a bit of trial and error.
Softwood cuttings are at the greatest risk of both drying out and rotting before rooting. This means you need to get them to root as quickly as possible by controlling the environment with heated propagators and close-fitting covers or similar protection. Hardwood cuttings are more mature, have greater food reserves, are less prone to drying out and rotting, and so can be rooted with less protection.
Cuttings need a balance of heat/warmth (particularly in the rooting medium), bright but indirect light, high humidity and adequate ventilation. If the environment is too warm and/or too dark the cuttings will grow tall and spindly. If it is too dry they will wilt, but if the compost is kept too wet or the atmosphere is too humid they may rot.
Although high humidity is important for most softwood cuttings, there are one or two exceptions – notably Chrysanthemum and Pelargonium, plants with furry leaves and succulents, which prefer a drier atmosphere and prefer good ventilation without close-fitting covers around their foliage.
Where to cut
The vast majority of stem cuttings are nodal cuttings – the stem is cut immediately below the swelling just below an axillary bud and leaf – the node.
Internodal cuttings are taken at a position between two nodes (the internode). This method can be used for more mature, woodier stems, as they are stronger and less likely to rot, and for Clematis.
Some plants are more difficult to root than others and you may need to take different types of stem cuttings at various times of the year. However, it is possible to help rooting of difficult plants by trying different methods.
- Using a hormone rooting powder or gel may improve rooting success, but they are not miracle cures and may have no effect.
- Some difficult plants respond well to wounding the stem by removing a thin, vertical sliver of bark up to 2.5cm (1in) long at the base of the cutting. Then dip the wound in hormone rooting compound.
- Cut the leaves of large-leaved plants, such as Hydrangea, in half horizontally as this reduces the leaf area and so reduces water loss.
- Other plants root better when removed from the parent plant with a small amount of main stem or ‘heel’.
Although some plants should be propagated at a specific time of year using a specific method, there are others that can be rooted from cuttings at just about any time of year. If the plant has produced sufficient growth, take the cutting and try and root it. If this is not successful, then you can always try again during a different season with a different method.
Take cuttings early in the morning when they are full of water (turgid) to avoid excessive wilting. Place them in a damp plastic bag, sealed to maintain humidity. Damp cotton wool placed in the bag will also reduce water loss. If the cutting material cannot be prepared immediately, place the bag in the salad drawer of the fridge; they can be kept here for up to 24 hours, but it is far better to use them well before then.
The four stem cuttings
There are four main types of stem cuttings – softwood, greenwood, semi-ripe and hardwood - together with several other useful variants on these listed below. They are taken at different times of the year, depending on when the necessary plant material becomes available and, consequently, from different types of stem growth. Evergreens can be treated with any of these methods.