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Horticulture 1000
H1092 - Plant propogation 2 - Choosing plant material for stem cuttings
Encouraging root growth Softwood cuttings
3

Choosing plant material for stem cuttings

Stem cuttings are divided into groups according to the type and stage of growth of the stem.

Wood types

In spring and early summer many perennial (long-lived) plants have new growth.  This new growth is soft and succulent and is called softwood tissue. The perennial plants may be trees, shrubs or herbaceous plants that have no woody tissue.

As the tree or shrub growth matures, the outside of the stem becomes more woody. If it still bends but will snap when broken it is known as semi-hardwood tissue.

When it is fully mature and woody it will not bend easily. This wood is known as hardwood tissue.

A stem or small branch may have hard, semi-hardwood and softwood along its length. It will look like this.

A stem or small branch may have hard, semi-hardwood and softwood along its length. It will look like this.

A node is the point on a stem where a leaf is attached and a bud forms.
A petiole is a leaf stalk.

Various factors will determine the type of cutting to make. You can propagate some plants using several methods.

You improve your chances of getting cuttings to grow roots if you choose the right time of year. Cuttings from some plants can be taken at different times of the year, but most plants can only be propagated from cuttings at specific times of the year. At other times of the year the plant material may not have enough stored energy to grow roots.

Common types of stem cuttings

                                                                               
Stem cuttingType of growthBest time of year to take this cuttingPlant examples
Softwood and herbaceous softwood Soft, green growth at the tip of the stem. Often it is the spring growth on a deciduous plant that is used. Spring or summer when plant is actively growing. chrysanthemum
      fuchsia
      geranium
      lavender
      azalea
      daisy
Semi-hardwood The stem is between the softwood and woody stage. This is spring growth that has started to mature. Mid-summer or early autumn camellia
      hebe
      leucodendron
      lavender
      box (Buxus)
Hardwood
      deciduous
Stem growth that grew during the spring and summer. The plant has lost its leaves and is dormant or resting. These cuttings should be longer than softwood cuttings and as thick as a pencil. Late autumn or winter blackcurrant
      gooseberry
      willow
      poplar
      rose
Hardwood evergreen The plant has leaves and mature wood. It is growing slowly. The material used for the cuttings should be the stem growth from spring and summer Late autumn to winter conifers (these are plants with needle-like leaves and cones, including plants from the Cypress species)

Photo examples of the different plant types used for cuttings.

Fuchsia - Softwood or semi hardwood cuttings depending on the time of year Azalea - Softwood or semi-hardwood cuttings Fuchsia - Softwood or semi-hardwood cuttings depending on the time of year Azalea - Softwood or semi-hardwood cuttingsLavender - Softwood or semi-hardwood cuttings Hebe - Semi-hardwood cuttings Lavender - Softwood or semi-hardwood cuttings Hebe - Semi-hardwood cuttingsPoplar - Deciduous hardwood cuttings Willow - Deciduous hardwood cuttings Poplar - Deciduous hardwood cuttings Willow - Deciduous hardwood cuttingsConifer - Evergreen hardwood cuttings Conifer - Evergreen hardwood cuttings Conifer - Evergreen hardwood cuttings Conifer - Evergreen hardwood cuttings

Getting cuttings to form roots

This is not magic. The secret lies in the growing cells called cambium. The cambium cells respond to the plant hormones that tell them to form new roots and shoots.

Cross-section of a woody stem showing the layer of cambium cells
Cross-section of a woody stem showing the layer of cambium cells.

How a cutting grows roots

When a stem is cut, callus tissue forms at the cut end. This tissue seals the wound. The new roots grow from the cambium tissue and push their way through the callus. Roots that grow from a stem are called adventitious roots. Rooting hormone encourages root development.

This is a cutting – a piece of stem cut from a plant

This is a cutting – a piece of stem cut from a plant.

From this cutting a new plant can grow

To take a stem cutting successfully, follow these general steps:

  • Take the cutting from a healthy, disease-free parent plant.
  • Use tools that are sharp and clean.
  • Choose the most suitable time of year.
  • The stem should  be 7–15 cm long (at least two nodes long).
  • Cut straight under a node.  In the node there is a concentration of the natural hormone auxin and stored food.
  • Remove large leaves or cut them in half to help prevent water loss through transpiration. The cutting is less likely to wilt.
  • Remove the lower leaves on the stem to  expose the cambium tissue and to help prevent water loss. They would also rot if they were below the surface of the media.
  • Remove any flower buds; otherwise the cutting will put energy into producing flowers rather than roots.
  • Treat the base of the cutting with plant rooting hormone to encourage roots to form.
  • Put the cutting into a growing media that holds water but drains away excess water, and has good aeration to ensure the bottom of the cutting does not rot.
  • Place the cutting in a light, airy, warm, sheltered environment with adequate water, oxygen, humidity, warmth and light.

Some types of cuttings may need specific treatment to encourage root formation. Specific treatment for the different types of cuttings is covered further on.

How you will know when roots have formed

  • Roots grow out of the drainage holes.
  • It is hard to gently pull the cutting upwards.
  • New leaves and shoots begin to grow.

Complete Activity 3A in your workbook

Key points   Key points

  • Cuttings are divided into groups according to the type and maturity of the wood.
  • Roots form from cambium tissue.

To make cuttings successfully:

  • take the cuttings from healthy parent plants at the most suitable time of the year
  • treat the base of the cutting with rooting hormone
  • make the cut just below a node. In the node there is a concentration of the natural hormone auxin and stored food
  • remove lower leaves and trim large leaves to reduce water loss and prevent wilting of the cutting
  • remove the lower leaves to expose the cambium tissue. They would rot if they were below the surface of the media.

What's next?

Go to: 4 Softwood cuttings.

 
Encouraging root growth Softwood cuttings